You can cast votes on questions, answers, and comments but they are limited per-day. You can only cast 30+10 votes in 24 hours.
Limited voting is in place to promote more deliberate voting decisions.
Limits on casting votes
- Maximum 30 all-purpose votes per day per user (up or down)
- Maximum 10 additional question-only votes per day per user. These may be cast at any time during the day. However once you reach the "N votes remaining" warnings, you won't get the additional 10 votes anymore. (Actually, it's a little trickier than that.)
Post votes (on questions / answers) and comment votes are two different pools and are tracked totally independently.