Why are there two static library formats in windows?

Question

C++ / C#

Good afternoon!
I noticed that in windows 2 static library formats: lib and a. Are these files identical in their format, meaning and content? Why did the unix extension move to windows?

Answer 1

.a is an archive of code: compiled but not linked. You would link statically with it during your program's final link step.
.lib can be either the same as .a, or a magical so-called "import library": a thin placeholder which causes you to require a .dll at runtime.

https://stackoverflow.com/questions/2337949/whats-...