Upvote is a method on the website Reddit by which users can signal their approval or support for a post. Upvotes move a post towards the top of the site, and they are a way to measure how many people approve of the content that is in a post. While other projects can use a voting system, the term upvoting has been associated with Reddit. Reddit says:

Vote. If you think something contributes to conversation, upvote it. If you think it does not contribute to the subreddit it is posted in or is off-topic in a particular community, downvote it.

Contexts

#reddit-lexicon (See: Reddit Glossary)