Sockets Programming:
- Building Socket Programs: course notes on how to build socket programs on Linux, Mac OS X/Xcode, and Windows 7/Visual Studio
- Command-line Options and Third-party Libraries: course notes on how to add these in various IDEs.
- Socket Programming: course notes introducing socket programming
- Warren Gay's Linux Socket Programming by Example
- FAQ: compiled from questions asked on comp.unix.programmer Usenet net news (1996)
- Beej's Guide to Network Programming: about as basic as the course notes above
Windows Sockets:
- O'Steen's Transitioning from UNIX to Windows Socket Programming
- Tangentsoft's Winsock Programmer's FAQ
- Microsoft's Windows Sockets 2
Sockets API Manual Pages
- Linux system calls
- Mac OS X Manual Pages (click "Section 2")
- Microsoft's Winsock Functions
- Microsoft's Windows Sockets Error Codes
- Microsoft's SO_REUSEADDR