Mentioning other accounts in your Tweet1.(n.) A Tweet may contain photos, GIFs, videos, and text. 2.(v.) The act of sending a Tweet. Tweets get shown in Twitter timelines or are embedded in websites and blogs. by including the @The @ sign is used to call out usernames in Tweets: "Hello @twitter!" People will use your @username to mention you in Tweets, send you a message or link to your profile. sign followed directly by their username is called a “mention”. Also refers to Tweets in which your @username was included.