diff --git a/documentation/content/en/books/handbook/introduction/_index.adoc b/documentation/content/en/books/handbook/introduction/_index.adoc
--- a/documentation/content/en/books/handbook/introduction/_index.adoc
+++ b/documentation/content/en/books/handbook/introduction/_index.adoc
@@ -113,47 +113,47 @@
 [[introduction-nutshell-users]]
 === Who Uses FreeBSD?
 
-FreeBSD has been known for its web serving capabilities - sites that run on FreeBSD include https://news.ycombinator.com/[Hacker News], http://www.netcraft.com/[Netcraft], http://www.163.com/[NetEase], https://signup.netflix.com/openconnect[Netflix], http://www.sina.com/[Sina], http://www.sony.co.jp/[Sony Japan], http://www.rambler.ru/[Rambler], http://www.yahoo.com/[Yahoo!], and http://www.yandex.ru/[Yandex]. 
+FreeBSD has been known for its web serving capabilities - sites that run on FreeBSD include link:https://news.ycombinator.com/[Hacker News], link:http://www.netcraft.com/[Netcraft], link:http://www.163.com/[NetEase], link:https://signup.netflix.com/openconnect[Netflix], link:http://www.sina.com/[Sina], link:http://www.sony.co.jp/[Sony Japan], link:http://www.rambler.ru/[Rambler], link:http://www.yahoo.com/[Yahoo!], and link:http://www.yandex.ru/[Yandex].
 
 FreeBSD's advanced features, proven security, predictable release cycle, and permissive license have led to its use as a platform for building many commercial and open source appliances, devices, and products.
 Many of the world's largest IT companies use FreeBSD:
 
-* http://www.apache.org/[Apache] - The Apache Software Foundation runs most of its public facing infrastructure, including possibly one of the largest SVN repositories in the world with over 1.4 million commits, on FreeBSD.
-* http://www.apple.com/[Apple] - OS X borrows heavily from FreeBSD for the network stack, virtual file system, and many userland components. Apple iOS also contains elements borrowed from FreeBSD.
-* http://www.cisco.com/[Cisco] - IronPort network security and anti-spam appliances run a modified FreeBSD kernel.
-* http://www.citrix.com/[Citrix] - The NetScaler line of security appliances provide layer 4-7 load balancing, content caching, application firewall, secure VPN, and mobile cloud network access, along with the power of a FreeBSD shell.
-* https://www.emc.com/isilon[Dell EMC Isilon] - Isilon's enterprise storage appliances are based on FreeBSD. The extremely liberal FreeBSD license allowed Isilon to integrate their intellectual property throughout the kernel and focus on building their product instead of an operating system.
-* http://www.quest.com/KACE[Quest KACE] - The KACE system management appliances run FreeBSD because of its reliability, scalability, and the community that supports its continued development.
-* http://www.ixsystems.com/[iXsystems] - The TrueNAS line of unified storage appliances is based on FreeBSD.
-* http://www.juniper.net/[Juniper] - The JunOS operating system that powers all Juniper networking gear (including routers, switches, security, and networking appliances) is based on FreeBSD. Juniper is one of many vendors that showcases the symbiotic relationship between the project and vendors of commercial products. Improvements generated at Juniper are upstreamed into FreeBSD to reduce the complexity of integrating new features from FreeBSD back into JunOS in the future.
-* http://www.mcafee.com/[McAfee] - SecurOS, the basis of McAfee enterprise firewall products including Sidewinder is based on FreeBSD.
-* http://www.netapp.com/[NetApp] - The Data ONTAP GX line of storage appliances are based on FreeBSD. In addition, NetApp has contributed back many features, including the new BSD licensed hypervisor, bhyve.
-* http://www.netflix.com/[Netflix] - The OpenConnect appliance that Netflix uses to stream movies to its customers is based on FreeBSD. Netflix has made extensive contributions to the codebase and works to maintain a zero delta from mainline FreeBSD. Netflix OpenConnect appliances are responsible for delivering more than 32% of all Internet traffic in North America.
-* http://www.sandvine.com/[Sandvine] - Sandvine uses FreeBSD as the basis of their high performance real-time network processing platforms that make up their intelligent network policy control products.
-* http://www.sony.com/[Sony] - The PlayStation 4 gaming console runs a modified version of FreeBSD.
-* http://www.sophos.com/[Sophos] - The Sophos Email Appliance product is based on a hardened FreeBSD and scans inbound mail for spam and viruses, while also monitoring outbound mail for malware as well as the accidental loss of sensitive information.
-* http://www.spectralogic.com/[Spectra Logic] - The nTier line of archive grade storage appliances run FreeBSD and OpenZFS.
-* https://www.stormshield.com[Stormshield] - Stormshield Network Security appliances are based on a hardened version of FreeBSD. The BSD license allows them to integrate their own intellectual property with the system while returning a great deal of interesting development to the community.
-* http://www.weather.com/[The Weather Channel] - The IntelliStar appliance that is installed at each local cable provider's headend and is responsible for injecting local weather forecasts into the cable TV network's programming runs FreeBSD.
-* http://www.verisign.com/[Verisign] - Verisign is responsible for operating the .com and .net root domain registries as well as the accompanying DNS infrastructure. They rely on a number of different network operating systems including FreeBSD to ensure there is no common point of failure in their infrastructure.
-* http://www.voxer.com/[Voxer] - Voxer powers their mobile voice messaging platform with ZFS on FreeBSD. Voxer switched from a Solaris derivative to FreeBSD because of its superior documentation, larger and more active community, and more developer friendly environment. In addition to critical features like ZFS and DTrace, FreeBSD also offers TRIM support for ZFS.
-* https://fudosecurity.com/en/[Fudo Security] - The FUDO security appliance allows enterprises to monitor, control, record, and audit contractors and administrators who work on their systems. Based on all of the best security features of FreeBSD including ZFS, GELI, Capsicum, HAST, and auditdistd.
+* link:http://www.apache.org/[Apache] - The Apache Software Foundation runs most of its public facing infrastructure, including possibly one of the largest SVN repositories in the world with over 1.4 million commits, on FreeBSD.
+* link:http://www.apple.com/[Apple] - OS X borrows heavily from FreeBSD for the network stack, virtual file system, and many userland components. Apple iOS also contains elements borrowed from FreeBSD.
+* link:http://www.cisco.com/[Cisco] - IronPort network security and anti-spam appliances run a modified FreeBSD kernel.
+* link:http://www.citrix.com/[Citrix] - The NetScaler line of security appliances provide layer 4-7 load balancing, content caching, application firewall, secure VPN, and mobile cloud network access, along with the power of a FreeBSD shell.
+* link:https://www.emc.com/isilon[Dell EMC Isilon] - Isilon's enterprise storage appliances are based on FreeBSD. The extremely liberal FreeBSD license allowed Isilon to integrate their intellectual property throughout the kernel and focus on building their product instead of an operating system.
+* link:http://www.quest.com/KACE[Quest KACE] - The KACE system management appliances run FreeBSD because of its reliability, scalability, and the community that supports its continued development.
+* link:http://www.ixsystems.com/[iXsystems] - The TrueNAS line of unified storage appliances is based on FreeBSD.
+* link:http://www.juniper.net/[Juniper] - The JunOS operating system that powers all Juniper networking gear (including routers, switches, security, and networking appliances) is based on FreeBSD. Juniper is one of many vendors that showcases the symbiotic relationship between the project and vendors of commercial products. Improvements generated at Juniper are upstreamed into FreeBSD to reduce the complexity of integrating new features from FreeBSD back into JunOS in the future.
+* link:http://www.mcafee.com/[McAfee] - SecurOS, the basis of McAfee enterprise firewall products including Sidewinder is based on FreeBSD.
+* link:http://www.netapp.com/[NetApp] - The Data ONTAP GX line of storage appliances are based on FreeBSD. In addition, NetApp has contributed back many features, including the new BSD licensed hypervisor, bhyve.
+* link:http://www.netflix.com/[Netflix] - The OpenConnect appliance that Netflix uses to stream movies to its customers is based on FreeBSD. Netflix has made extensive contributions to the codebase and works to maintain a zero delta from mainline FreeBSD. Netflix OpenConnect appliances are responsible for delivering more than 32% of all Internet traffic in North America.
+* link:http://www.sandvine.com/[Sandvine] - Sandvine uses FreeBSD as the basis of their high performance real-time network processing platforms that make up their intelligent network policy control products.
+* link:http://www.sony.com/[Sony] - The PlayStation 4 gaming console runs a modified version of FreeBSD.
+* link:http://www.sophos.com/[Sophos] - The Sophos Email Appliance product is based on a hardened FreeBSD and scans inbound mail for spam and viruses, while also monitoring outbound mail for malware as well as the accidental loss of sensitive information.
+* link:http://www.spectralogic.com/[Spectra Logic] - The nTier line of archive grade storage appliances run FreeBSD and OpenZFS.
+* link:https://www.stormshield.com[Stormshield] - Stormshield Network Security appliances are based on a hardened version of FreeBSD. The BSD license allows them to integrate their own intellectual property with the system while returning a great deal of interesting development to the community.
+* link:http://www.weather.com/[The Weather Channel] - The IntelliStar appliance that is installed at each local cable provider's headend and is responsible for injecting local weather forecasts into the cable TV network's programming runs FreeBSD.
+* link:http://www.verisign.com/[Verisign] - Verisign is responsible for operating the .com and .net root domain registries as well as the accompanying DNS infrastructure. They rely on a number of different network operating systems including FreeBSD to ensure there is no common point of failure in their infrastructure.
+* link:http://www.voxer.com/[Voxer] - Voxer powers their mobile voice messaging platform with ZFS on FreeBSD. Voxer switched from a Solaris derivative to FreeBSD because of its superior documentation, larger and more active community, and more developer friendly environment. In addition to critical features like ZFS and DTrace, FreeBSD also offers TRIM support for ZFS.
+* link:https://fudosecurity.com/en/[Fudo Security] - The FUDO security appliance allows enterprises to monitor, control, record, and audit contractors and administrators who work on their systems. Based on all of the best security features of FreeBSD including ZFS, GELI, Capsicum, HAST, and auditdistd.
 
 FreeBSD has also spawned a number of related open source projects:
 
-* http://bsdrp.net/[BSD Router] - A FreeBSD based replacement for large enterprise routers designed to run on standard PC hardware.
-* https://www.truenas.com/[TrueNAS] is a Network Attached Storage (NAS) software that shares and protects data from modern-day threats like ransomware and malware. TrueNAS makes it easy for users and client devices to access shared data through virtually any sharing protocol.
-* https://ghostbsd.org/[GhostBSD] - is derived from FreeBSD, uses the GTK environment to provide a beautiful looks and comfortable experience on the modern BSD platform offering a natural and native UNIX(R) work environment.
-* http://mfsbsd.vx.sk/[mfsBSD] - A toolkit for building a FreeBSD system image that runs entirely from memory.
-* https://xigmanas.com/[XigmaNAS] - A file server distribution based on FreeBSD with a PHP powered web interface.
-* http://www.opnsense.org/[OPNSense] - OPNsense is an open source, easy-to-use and easy-to-build FreeBSD based firewall and routing platform. OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. It brings the rich feature set of commercial offerings with the benefits of open and verifiable sources.
-* https://www.midnightbsd.org[MidnightBSD] - is a FreeBSD derived operating system developed with desktop users in mind. It includes all the software you'd expect for your daily tasks: mail, web browsing, word processing, gaming, and much more.
-* https://www.nomadbsd.org[NomadBSD] - is a persistent live system for USB flash drives, based on FreeBSD. Together with automatic hardware detection and setup, it is configured to be used as a desktop system that works out of the box, but can also be used for data recovery, for educational purposes, or to test FreeBSD's hardware compatibility.
-* http://www.pfsense.org/[pfSense] - A firewall distribution based on FreeBSD with a huge array of features and extensive IPv6 support.
-* http://zrouter.org/[ZRouter] - An open source alternative firmware for embedded devices based on FreeBSD. Designed to replace the proprietary firmware on off-the-shelf routers.
+* link:http://bsdrp.net/[BSD Router] - A FreeBSD based replacement for large enterprise routers, designed to run on standard PC hardware.
+* link:https://www.truenas.com/[TrueNAS] is a Network Attached Storage (NAS) software that shares and protects data from modern-day threats like ransomware and malware. TrueNAS makes it easy for users and client devices to access shared data through virtually any sharing protocol.
+* link:https://ghostbsd.org/[GhostBSD] is derived from FreeBSD, uses the GTK environment to provide beautiful looks and comfortable experience on the modern BSD platform offering a natural and native UNIX(R) work environment.
+* link:http://mfsbsd.vx.sk/[mfsBSD] - A toolkit for building a FreeBSD system image that runs entirely from memory.
+* link:https://xigmanas.com/[XigmaNAS] - A file server distribution based on FreeBSD with a PHP powered web interface.
+* link:http://www.opnsense.org/[OPNSense] is an open source, easy-to-use and easy-to-build FreeBSD based firewall and routing platform. OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. It brings the rich feature set of commercial offerings with the benefits of open and verifiable sources.
+* link:https://www.midnightbsd.org[MidnightBSD] is a FreeBSD derived operating system developed with desktop users in mind. It includes all the software you'd expect for your daily tasks: mail, web browsing, word processing, gaming, and much more.
+* link:https://www.nomadbsd.org[NomadBSD] is a persistent live system for USB flash drives, based on FreeBSD. Together with automatic hardware detection and setup, it is configured to be used as a desktop system that works out of the box, but can also be used for data recovery, for educational purposes, or to test FreeBSD's hardware compatibility.
+* link:http://www.pfsense.org/[pfSense] - A firewall distribution based on FreeBSD with a huge array of features and extensive IPv6 support.
+* link:http://zrouter.org/[ZRouter] - An open source alternative firmware for embedded devices based on FreeBSD. Designed to replace the proprietary firmware on off-the-shelf routers.
 
-A list of https://www.freebsdfoundation.org/about/testimonials/[testimonials from companies basing their products and services on FreeBSD] can be found at the FreeBSD Foundation website.
-Wikipedia also maintains a https://en.wikipedia.org/wiki/List_of_products_based_on_FreeBSD[list of products based on FreeBSD].
+A list of link:https://www.freebsdfoundation.org/about/testimonials/[testimonials from companies basing their products and services on FreeBSD] can be found at the FreeBSD Foundation website.
+Wikipedia also maintains a link:https://en.wikipedia.org/wiki/List_of_products_based_on_FreeBSD[list of products based on FreeBSD].
 
 [[history]]
 == About the FreeBSD Project
@@ -210,24 +210,24 @@
 [[development]]
 === The FreeBSD Development Model
 
-The development of FreeBSD is a very open and flexible process, being literally built from the contributions of thousands of people around the world, as can be seen from our extref:{contributors}[list of contributors].
+The development of FreeBSD is a extref:{dev-model}[very open and flexible process], being literally built from the contributions of thousands of people around the world, as can be seen from our extref:{contributors}[list of contributors].
 FreeBSD's development infrastructure allow these thousands of contributors to collaborate over the Internet.
-We are constantly on the lookout for new developers and ideas, and those interested in becoming more closely involved with the project need simply contact us at the {freebsd-hackers}.
-The {freebsd-announce} is also available to those wishing to make other FreeBSD users aware of major areas of work.
+We are constantly on the lookout for new developers and ideas, and those interested in becoming more closely involved with the project need simply contact us at the link:{freebsd-hackers}.
+The link:{freebsd-announce} is also available to those wishing to make other FreeBSD users aware of major areas of work.
 
 Useful things to know about the FreeBSD Project and its development process, whether working independently or in close cooperation:
 
 The Git repositories[[development-cvs-repository]]::
-For several years, the central source tree for FreeBSD was maintained by http://www.nongnu.org/cvs/[CVS] (Concurrent Versions System), a freely available source code control tool.
-In June 2008, the Project switched to using https://subversion.apache.org/[SVN] (Subversion).
+For several years, the central source tree for FreeBSD was maintained by link:http://www.nongnu.org/cvs/[CVS] (Concurrent Versions System), a freely available source code control tool.
+In June 2008, the Project switched to using link:https://subversion.apache.org/[SVN] (Subversion).
 The switch was deemed necessary, as the technical limitations imposed by CVS were becoming obvious due to the rapid expansion of the source tree and the amount of history already stored.
 The Documentation Project and Ports Collection repositories also moved from CVS to SVN in May 2012 and July 2012, respectively.
-In December 2020, the Project https://www.freebsd.org/status/report-2020-10-2020-12.html#Git-Migration-Working-Group[migrated Source and Documentation repositories] to https://git-scm.com/[Git], with https://www.freebsd.org/status/report-2021-04-2021-06/#_git_migration_working_group[Ports following suit] in April 2021.
+In December 2020, the Project link:https://www.freebsd.org/status/report-2020-10-2020-12.html#Git-Migration-Working-Group[migrated Source and Documentation repositories] to link:https://git-scm.com/[Git], with link:https://www.freebsd.org/status/report-2021-04-2021-06/#_git_migration_working_group[Ports following suit] in April 2021.
 Please refer to the crossref:cutting-edge[synching, Obtaining the Source] section for more information on obtaining the FreeBSD `src/` repository and crossref:ports[ports-using, Using the Ports Collection] for details on obtaining the FreeBSD Ports Collection.
 
 The committers list[[development-committers]]::
 The _committers_ are the people who have _push_ access to the Git repository, and are authorized to make modifications to the FreeBSD source (the term "committer" comes from `commit`, the source control command which is used to bring new changes into the repository).
-Anyone can submit a bug to the https://bugs.FreeBSD.org/submit/[Bug Database].
+Anyone can submit a bug to the link:https://bugs.FreeBSD.org/submit/[Bug Database].
 Before submitting a bug report, the FreeBSD mailing lists, IRC channels, or forums can be used to help verify that an issue is actually a bug.
 
 The FreeBSD core team[[development-core]]::
@@ -253,7 +253,7 @@
 
 Outside contributors::
 Last, but definitely not least, the largest group of developers are the users themselves who provide feedback and bug fixes to us on an almost constant basis.
-The primary way of keeping in touch with FreeBSD's more non-centralized development is to subscribe to the {freebsd-hackers} where such things are discussed.
+The primary way of keeping in touch with FreeBSD's more non-centralized development is to subscribe to the link:{freebsd-hackers} where such things are discussed.
 See crossref:eresources[eresources, Resources on the Internet] for more information about the various FreeBSD mailing lists.
 +
 extref:{contributors}[The FreeBSD Contributors List] is a long and growing one, so why not join it by contributing something back to FreeBSD today?
@@ -269,10 +269,11 @@
 === Third Party Programs
 
 In addition to the base distributions, FreeBSD offers a ported software collection with thousands of commonly sought-after programs.
-At the time of this writing, there were over {numports} ports! The list of ports ranges from http servers, to games, languages, editors, and almost everything in between.
-The entire Ports Collection requires approximately {ports-size}.
+The list of ports ranges from HTTP servers, to games, languages, editors, and almost everything in between.
+There are about {numports} ports; the entire Ports Collection requires approximately {ports-size}.
 To compile a port, you simply change to the directory of the program you wish to install, type `make install`, and let the system do the rest.
 The full original distribution for each port you build is retrieved dynamically so you need only enough disk space to build the ports you want.
+
 Almost every port is also provided as a pre-compiled "package", which can be installed with a simple command (`pkg install`) by those who do not wish to compile their own ports from source.
 More information on packages and ports can be found in crossref:ports[ports,Installing Applications: Packages and Ports].
 
@@ -295,4 +296,4 @@
 The FreeBSD FAQ::
 [.filename]#link:file://localhost/usr/local/share/doc/freebsd/en/books/faq/book.html[/usr/local/share/doc/freebsd/en/books/faq/book.html]#
 
-You can always find the up to date copy at https://docs.FreeBSD.org/[https://docs.FreeBSD.org/].
+You can always find up to date documentation at link:https://docs.FreeBSD.org/[https://docs.FreeBSD.org/].