Congratulations! You've reached the 200 rep/day cap, which applies to reputation from upvotes, downvotes, and suggested edits. (N.B. Stack Exchange uses UTC time, so 1 day is from midnight UTC of one day to midnight UTC of the next.)
Past the rep cap, you can't earn any more reputation until the next day; however, I'm happy to let you know it's already the next day (technically, you reached the rep cap yesterday SE-time), so you can still earn rep right now.
There's a twofold reason there's a cap in place: 1) we don't want people to burn out too quickly, so we encourage you not to spend too much time here :), and 2) we don't want someone to gain a lot of privileges that they might unknowingly abuse for one post that's really, really popular because it's been linked that day on Reddit (it's better if the votes are spread out over time, as that's usually more indicative of good quality that keeps getting upvoted instead of linkspammed on some site).