A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
questions concerning actual teletype devices, including the famous model 33 teletype.
Questions about character-sets, either from a standardization point of view, or in terms of the repertoire implemented by particular equipment.
Questions about the Algol languages: Algol 58 (IAL), Algol 60, Algol 68.