1. libs for hardware

stored in /lib/modules/<ver>

2. libs for apps

stored in /usr/lib (e.g., /usr/lib/libbz.so.1

3. Building .a (ar)chive files with ar(1)

The contents of an ar (/usr/lib/libbz.a) are the compiled object files .o
List contents: ar t /usr/lib/libbz2.a
Build:
    ar r libbz.a *.o
    ranlib libbz.a (or ar -s libbz.a)