A hashtag is where a social media user creates their own search term for a topic and by using a hash (#) creates a hyperlink to a page which links all identically hashtagged content. This allows any user to search for content with this tag quickly, and to join in discussions.
Whilst it's great to join in with trending discussions and share your images and thoughts with others, it's important to consider what terms you're using and how they would look to an employer or university. Hashtags can make your content searchable, so think about who you want to see it. Tagging friends and family in photographs and links can also backfire, especially if they don't want to be publicly linked to that content.
To find out more about what affects your online reputation, click here