Spell checkers are specialized software applications that highlight words which may not have been spelled correctly.
They typically use a wide range of notification methods to alert the user that a word is misspelled, ranging from underlining the word to playing a predefined sound.
These utilities are usually based on two components, a set of rules for text scanning and word identifying, and an algorithm that compares the words to the built-in dictionary, an integrated list that contains correct words
Spell checkers may be either standalone applications that are capable of monitoring third-party programs, or they can be integrated within larger products, like office suites, word processors, email clients or even browsers.