Pangram
A pangram is a sentence or phrase that contains every letter of the alphabet at least once.
The famous English example is "The quick brown fox jumps over the lazy dog", which manages all twenty-six letters in thirty-five. Typographers and keyboard testers use pangrams because a single line shows every glyph in a typeface and exercises every key.
A perfect pangram uses each letter exactly once, so it is exactly twenty-six letters long. English has very few that read as sentences at all, and the ones that exist lean hard on initials and proper nouns: "Mr Jock, TV quiz PhD, bags few lynx" is the usual example.
The word carries a second meaning in word games, where a pangram is an answer that uses every letter available in that day's puzzle. Games built on a fixed letter set typically award a large bonus for finding one. A pangrammatic crossword is a third thing again: a grid whose answers, taken together, use all twenty-six letters, which constructors treat as a self-imposed flourish rather than something solvers are meant to notice.