Libtool requires intimate knowledge of your compiler suite and operating system to be able to create shared libraries and link against them properly. When you install the libtool distribution, a system-specific libtool script is installed into your binary directory.
However, when you distribute libtool with your own packages (see Including libtool in your package), you do not always know the compiler suite and operating system that are used to compile your package.
For this reason, libtool must be configured before it can be
used. This idea should be familiar to anybody who has used a GNU
configure script. configure runs a number of tests for
system features, then generates the Makefiles (and possibly a
config.h header file), after which you can run make and
build the package.
Libtool adds its own tests to your configure script to
generate a libtool script for the installer’s host machine.