[linux] What are libtool's .la file for?

What are libtool's .la files for? How are they used with a shared object?

I found very good explanation about .la files here http://openbooks.sourceforge.net/books/wga/dealing-with-libraries.html

Summary (The way I understood): Because libtool deals with static and dynamic libraries internally (through --diable-shared or --disable-static) it creates a wrapper on the library files it builds. They are treated as binary library files with in libtool supported environment.

According to http://blog.flameeyes.eu/2008/04/14/what-about-those-la-files, they're needed to handle dependencies. But using pkg-config may be a better option:

In a perfect world, every static library needing dependencies would have its own .pc file for pkg-config, and every package trying to statically link to that library would be using pkg-config --static to get the libraries to link to.