In college, I was never interested in theory. I never read it. No matter how much I tried, I was unable to read stuff and not know what was actually happening practically. Like for example, in my course on automata theory, my professor told me everything possibly related to the mathematical aspect of it, but not even once did he mention where it would be used practically. This is just an example.

I managed to pass my college and interned with a company also, where I did a project and thankfully they didn't bother about my grades, as they were above average.

Now, I am interested in knowing what subjects should a CS student must absolutely and positively be aware of? Subjects that can have relevance in the industry. This is because I have some free time on my hands and it would help me better to have a good understanding of them.

What are your suggestions? Like for one, algorithms is one subject.