RE: theory of lib*.a

[Michaël <michaelgrunewald yahoo fr>]

In fact .so stands for shared object, and such modules are dynamically 
loadable or dynamically linkable :

This means code of shared objects can be shared between applications (only 
one code image is loaded in memory, while with static linking one code image 
is loaded for each application using it, because it is contained in the code) 
so it keeps memory (on disk and on RAM) for more useful usages (this is 
dynamic linking) or you can load functions at the time you need them(dynamic 
loading) this is used in writing plugins, or in applications that allows 
user-compiled-by functions to be used (z.b. scilab). 

I advise you to read man dlopen to know more.