A separate program or function within a word processing or other text entry program that tests for correctly spelled words. Spell checkers can test spelling on the fly as the user types, or they may be able to examine a marked block, entire document or group of documents. Advanced systems correct common typos and misspellings on the fly.
Spell checkers simply compare words to a dictionary of words, and the wrong use of a correctly spelled word such as "bear" and "bare" cannot be detected. See grammar checker