A spell checker is a software tool designed to identify and correct spelling errors in text. It works by comparing words in a document against a database of correctly spelled words. When it finds a misspelled word, it often suggests alternatives, helping users improve their writing. Spell checkers are commonly integrated into word processing programs like Microsoft Word and email clients. They can also be found in web browsers and mobile applications, making it easier for users to write accurately across different platforms. While helpful, spell checkers may not catch all errors, especially with homophones or context-specific words.