Tone indicators start with a forward slash (/), followed by a short series of letters, usually a shortening of another word.
Various other punctuation marks were proposed over the following centuries to denote irony, but none gained popular usage.
[3] The syntax of modern tone indicators stems from /s, which has long been used on the internet to denote sarcasm.
A tone indicator on the internet often takes the form of a forward slash (/) followed by an abbreviation of a relevant adjective; alternatively, a more detailed textual description (e. g., / friendly, caring about your well-being) may be used.
Tone indicators are used to explicitly state the author's intent, instead of leaving the message up to interpretation.