Upvote means you find the content helpful, interesting, amusing, etc. It's your way of saying you like it and want to see more content like it! The thumbs down button is for downvoting. It means you think the content detracts from Glow Community because it's offensive or irrelevant.
Your upvotes will push interesting content to the top of the page, meanwhile your downvotes will push them down.
If a post or comments receives enough downvotes it'll be hidden by the message “Hidden due to downvotes” and will not be visible unless clicked upon. But please take note: Downvotes should be used only for irrelevant or offensive comments, and not ideas you simply disagree with. In fact, don’t be afraid to upvote a comment you disagree with if you think it is furthering the discussion.
The purpose of this feature is to help you quickly surface interesting, helpful content, while simultaneously burying objectionable, offensive content. It's your Community, your call!