A grammar checker is a program, or part of a program, that attempts to find grammatical errors in written text. These errors can include improper sentence structure, misspelled words, incorrect word usage (using there instead of their), and misplaced punctuation. Grammar checkers are often a feature of a larger program, such as a word processor, but can be offered as a standalone application. Some grammar checkers will also check phrasing, style consistency, and active and passive voice and perform readability testing.
A grammar checker uses natural language processing and grammatical rules to identify misspelling and other language errors. A grammar checker takes each sentence within a text, looks up each word in its extensive dictionary, and tries to parse the sentence into a form that matches correct grammar. The parsing process is used to detect words that fail to follow accepted usage.
Writers use a grammar checker to ensure grammatical correctness and consistency within their writing. Most times, a checker will indicate an error has occurred in the writing with a visual aid. For example, Microsoft Word places a red squiggly line under misspelled words and a green squiggly line under incorrect phrases.
Using a grammar checker can save time when proofreading a document, provide useful feedback to help a user learn about grammar, and ensure that writing is error-free, which is critical when writing important documents.
As grammar is complex and ever-changing, these programs are far from perfect, so users should never rely fully on one and should continue to use their own judgement when writing. While computer programming languages have specific syntax and grammar, the same can’t be said for natural languages, which have many rule exceptions.
Natural languages do not have to comply with strict rules, and they are not constrained by specific syntax. Hence, achieving accurate and complete grammatical verification is difficult.
Popular standalone grammar checkers include:
Popular word processors with grammar-checking capabilities include: