What is modpost ?

[Pritam Bankar]

Hi guys,
I want to confirm my understanding regarding modpost and Module.Symvers files.
>From my understanding
                 a. modpost is used to add versioning information to module.
                 b. modpost is also used to create mod.c and
Module.Symvers files per module
                 c. then we compile all *.mod.c files and link it to .ko

Is my understanding correct ? For what else purpose modpost is useful
? What is specific data in mod.c file ?

Thanks,
Pritam