In its most general sense, a topic refers to a subject area. It could be a controversy, a problem, or even a pastime or interest. If you're thinking you could choose a topic from pretty much any subject area, you're right! But that's not to say every topic would be right for you. The topic that's right for you depends on what you're curious about. Indeed, when choosing a topic, the most important question you can ask yourself is this one: "What makes me curious?" —ProQuest Research Companion
These Pro/Con databases are a great resource for exploring topics that might interest you