Hashtags serve a few different purposes on Twitter. At a basic level, hashtags "categorize" Tweets, which makes it easier for people to find your Tweet (and to find Tweets that are related to a specific topic). So if you add #edtech to your Tweet, people who search for "edtech" Tweets can see what you have to say!
Hashtags can also be used to create organized or even impromptu chats which take place across the world using Twitter. Education chats are extremely popular on Twitter, and there are hundreds of different education chats for all subjects, grade levels, and interests. There is an official list of these Twitter edchats, and you can also find the list organized by schedule (day of the week and time).
Too many hashtags to pick from? Don't be afraid to start simple! The graphic below summarizes some of the best education hashtags to use in your Tweets. Start with some of the most popular ones, then work your way into using more specific hashtags depending on what you're Tweeting about. You can also click to download the graphic as a PDF for printing.