In adventure games, a text parser takes typed input (a command) from the player and simplifies it to something the game can understand. Usually, words with the same meaning are turned into the same word (e.g. "take" and "get") and certain filler words are dropped (e.g. articles, or the "at" in "look at rock").
The parser makes it easier for the game's author to react on input. The author does not have to write special code to process the commands "get the gem", "take the gem", "get gem", "take gem", "take the precious gem", etc. separately, as the parser will have stripped the input down to something like "take gem".
For the player, the game is more flexible, as the game has a larger vocabulary, and there are fewer guess-the-verb and guess-the-noun problems.
Parsers are used in early interactive fiction games like the Zork series, and more recently in games created by systems like Inform and TADS.
Famous quotes containing the word text:
“The power of a text is different when it is read from when it is copied out.... Only the copied text thus commands the soul of him who is occupied with it, whereas the mere reader never discovers the new aspects of his inner self that are opened by the text, that road cut through the interior jungle forever closing behind it: because the reader follows the movement of his mind in the free flight of day-dreaming, whereas the copier submits it to command.”
—Walter Benjamin (1892–1940)