APIs

I want to get into software development. I know the various languages most companies use, and new languages are fairly easy to pick up. The problem I have is working out what APIs and interfaces I should be learning. I've spent time poking around MSDN, but it's a huge place and I've no idea where to start. What are the key things I should learn about .NET, WPF, ASP and the like, and what are good tutorials/ guides/ books you would recommend to learn them?

>>1
This depends on what you want to develop and the platform.

The old unix C API is a good place to start because it is quite common and many APIs are based on it.

http://www.youtube.com/watch?v=wK4zX-uGhiU

Start with driver interfaces, protocols and file formats. Everything else consists mostly of bloated frameworks and junk, with an occasional specialized utility library.

Easy: libCurl.
Normal: POSIX.
Hard: Win32, Direct3D, OpenGL.
Lunatic: GTK+.

Extra: X11.
Phantasm: ALSA.

I'll look into the low level stuff. I think what I really want is something that's going to make me employable, though. Is there a lot of demand for the fundamental stuff, or are there some good guides or tutorials on WPF /.NET I should look into?

>>4
NULL jokes aside, Win32 is not harder than POSIX. There are just more APIs because it has everything: filesystem, graphics, text, other UI stuff, etc. Compare it with POSIX+OpenGL+FreeType+... and you will see what's really harder.

>>6
Wherever POSIX and Win32 provide the same functionality, the POSIX way is simpler.
http://msdn.microsoft.com/en-us/library/windows/desktop/aa363858%28v=vs.85%29.aspx
http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html

>>4
ALSA's not that bad. I've written for it. It's just accounting for virtually every possible set of capabilities, and it manages to do a damn good job at that. Mind you, I don't like writing for ALSA by any means.