text: Users can group posts together by topic or type by use of hashtags – words or phrases prefixed with a "#" sign. Similarly, the "@" sign followed by a username is used for mentioning or replying to other users. In 2014, Twitter introduced hashflags, special hashtags that automatically generate a custom emoji next to them for a certain period of time. Hashflags may be generated by Twitter themselves or be purchased by corporations. To repost a message from another X user and share it with one's own followers, a user can click the repost button within the post. Users can reply to other accounts' replies. Users can hide replies to their messages and select who can reply to each of their tweets before sending them: anyone, accounts who follow the poster, specific accounts, or none.
  The original, strict 140 character limit was gradually relaxed. In 2016, Twitter announced that attachments, links, and media such as photos, videos, and the person's handle, would no longer count; a user photo post used to count for around 24 characters. In 2017, Twitter handles were similarly excluded. The same year, Twitter doubled its historical 140-character-limitation to 280. Under the new limit, glyphs are counted as a variable number of characters, depending upon the script they are from. In 2023, Twitter announced that Twitter Blue users could create posts with up to 4,000 characters in length.