Zalgo text, also known as cursed text or glitch text due to the nature of its use, is digital text that has been modified with numerous combining characters, Unicode symbols used to add diacritics above or below letters, to appear frightening or glitchy.
Named for a 2004 Internet creepypasta story that ascribes it to the influence of an eldritch deity, Zalgo text has become a significant component of many Internet memes, particularly in the "surreal meme" culture. The formatting of Zalgo text also allows it to be used to halt or impair certain computer functions, whether intentionally or not.