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.