Any particular interest in a topic?

(Jeopardy) CTFs can be categorized like this:

Anything website like SQLi, XSS, CSRF, SSRF, URL enumeration via tools like gobuster, ...

Stands for reverse engineering. You are given a binary and you need to find a way to cause a overflow (buffer, stack ,integer, ...) and exploit that overflow (for example). Usually, you're only given the binary so you can locally develop our exploit. When you're done, you can run this exploit against a binary running on a server where you have to leak the flag from memory or disk.

Something is encrypted and you need to find a way to break the encryption. Usually, you don't need to find the key. There are other ways to get access to the plaintext or be able to guess what the plaintext probably is.

This is kind of a catch-all category. It's usually just about knowing your way around linux or tech stacks. So you could say it's all about RTFM. For example, the solution might just be to run grep -R against a directory full of random data. But with the right, clever pattern, you'll find the needle in the haystack (the flag). (Don't underestimate this category now. This was just a beginner example, lol)

This are all categories I can think of. There are more out there but these categorizes aren't standardized so it's natural that every CTF might have their own way of naming the categories of their challenges.

For example, here's the category list from picoCTF Gym (picoGym):