I've been searching for a detailed definition about what computer science is about for years, when one day I came across these two documents: Computing curricula 2005 report and Computer Science Curricula 2013. The latter, more importantly, lists the knowledge areas and their relative content that an undergraduate student in computer science should know. The content of each knowledge area is divided in core-topics and elective-topics.
What I want to ask is:
1) What exactly are the knowledge areas? Are they the fields of computer science where Ph.D. students can focus their research? If yes, then how about architecture and organization (AR)? Isn't it the knowledge area where only computer/electrical engineers can focus their research?
2) Is this curricula applicable worldwide or does each country have its own?
3) Some topics are elective. How can I study the elective topics I'm interested in since my university didn't have enough time and resources to teach them?
Any answer will be appreciated.