Most people think of topics like these when they think of ComputerScience:
* Data structures (how to store stuff so it's small/easily accessible/useful for something)
* Algorithms (how to do stuff fast)
* Operating systems (how to do lots of stuff at once)
* Graphics (how to generate/process pretty pictures)
* Networking (how to communicate with other stuff)
* Architecture (how to build stuff that does stuff, and hopefully does it fast)
Though lately, more and more things are happening with machine learning and artificial intelligence.