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diff --git a/share/man/man3/intro.3 b/share/man/man3/intro.3
--- a/share/man/man3/intro.3
+++ b/share/man/man3/intro.3
@@ -28,7 +28,7 @@
.\" @(#)intro.3 8.1 (Berkeley) 6/5/93
.\" $FreeBSD$
.\"
-.Dd December 18, 2021
+.Dd September 15, 2022
.Dt INTRO 3
.Os
.Sh NAME
@@ -272,13 +272,132 @@
.It Pa /usr/lib/libm_p.a
the math library compiled for profiling
.El
+.Sh LIBRARY TYPES
+The system libraries are located in
+.Pa /usr/lib .
+Typically, a library will have a number of variants:
+.Bd -unfilled -offset indent
+libc.a
+libc_p.a
+libc.so.30.1
+.Ed
+.Pp
+Libraries with an
+.Sq .a
+suffix are static.
+When a program is linked against a library, all the library code
+will be linked into the binary.
+This means the binary can be run even when the libraries are unavailable.
+However, it can be inefficient with memory usage.
+The C compiler,
+.Xr cc 1 ,
+can be instructed to link statically by specifying the
+.Fl static
+flag.
+.Pp
+Libraries with a
+.Sq _p.a
+suffix are profiling libraries.
+They contain extra information suitable for analysing programs,
+such as execution speed and call counts.
+This in turn can be interpreted by utilities such as
+.Xr gprof 1 .
+The C compiler,
+.Xr cc 1 ,
+can be instructed to generate profiling code,
+or to link with profiling libraries, by specifying the
+.Fl pg
+flag.
+.Pp
+Libraries with a
+.Sq .so.X.Y
+suffix are dynamic libraries.
+When code is compiled dynamically, the library code that the application needs
+is not linked into the binary.
+Instead, data structures are added containing information about which dynamic
+libraries to link with.
+When the binary is executed, the run-time linker
+.Xr ld.so 1
+reads these data structures, and loads them at a virtual address using the
+.Xr mmap 2
+system call.
+.Pp
+.Sq X
+represents the major number of the library, and
+.Sq Y
+represents the minor number.
+In general, a binary will be able to use a dynamic library with a differing
+minor number, but the major numbers must match.
+In the example above, a binary linked with minor number
+.Sq 3
+would be linkable against libc.so.30.1,
+while a binary linked with major number
+.Sq 31
+would not.
+.Pp
+The advantages of dynamic libraries are that multiple instances of the same
+program can share address space, and the physical size of the binary is
+smaller.
+The disadvantage is the added complexity that comes with loading the
+libraries dynamically, and the extra time taken to load the libraries.
+Of course, if the libraries are not available, the binary will be unable
+to execute.
+The C compiler,
+.Xr cc 1 ,
+can be instructed to link dynamically by specifying the
+.Fl shared
+flag, although on systems that support it, this will be the default and
+need not be specified.
+.Pp
+Shared libraries, as well as static libraries on architectures which produce
+position-independent executables
+.Pq PIEs
+by default, contain position-independent code
+.Pq PIC .
+Normally, compilers produce relocatable code.
+Relocatable code needs to be modified at run-time, depending on where in
+memory it is to be run.
+PIC code does not need to be modified at run-time, but is less efficient than
+relocatable code.
+The C compiler,
+.Xr cc 1 ,
+can be instructed to generate PIC code by specifying the
+.Fl fpic
+or
+.Fl fPIC
+flags.
+.Pp
+With the exception of dynamic libraries, libraries are generated using the
+.Xr ar 1
+utility.
+The libraries contain an index to the contents of the library,
+stored within the library itself.
+The index lists each symbol defined by a member of a library that is a
+relocatable object file.
+This speeds up linking to the library, and allows routines in the library
+to call each other regardless of their placement within the library.
+The index is created by
+.Xr ranlib 1
+and can be viewed using
+.Xr nm 1 .
+.Pp
+The building of profiling versions of libraries can
+be prevented by setting the variable
+.Dv WITHOUT_PROFILE
+in
+.Pa /etc/src.conf .
+See
+.Xr make.conf 5
+for more details.
.Sh SEE ALSO
.Xr cc 1 ,
.Xr ld 1 ,
.Xr nm 1 ,
.Xr intro 2 ,
.Xr math 3 ,
-.Xr stdio 3
+.Xr stdio 3 ,
+.Xr make.conf 5 ,
+.Xr src.conf 5
.Sh HISTORY
An
.Nm

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