lfs-book/appendixa/glibc-desc.xml

<sect2>
<title>Contents</title>

<para>
The Glibc package contains the GNU C Library.
</para>

</sect2>

<sect2><title>Description</title>

<para>
The C Library is a collection of commonly used functions in programs.
This way a programmer doesn't need to create his own functions for every
single task. The most common things like writing a string to the screen
are already present and at the disposal of the programmer.
</para>

<para>
The C library (actually almost every library) come in two flavors:
dynamic ones and static ones. In short when a program uses a static C
library, the code from the C library will be copied into the executable
file. When a program uses a dynamic library, that executable will not
contain the code from the C library, but  instead a routine that loads
the functions from the library at the time the program is run. This
means a significant decrease in the file size of a program. The 
documentation that comes with the C Library describes this in more
detail, as it is too complicated to explain here in one or two lines.
</para>

</sect2>