The spell-check and grammar-check tools included in word processor programs provide valuable proofreading assistance. These programs catch errors so quickly and efficiently that rereading a document yourself for errors may seem unnecessary. However, these automated tools are not perfect. If you know which problems to look for in your word processor's spell- or grammar-check, you can combine them with your own editing to create more polished work.

Similar Words

Spell-check programs automatically correct common words when you mistype letters, such as replacing “hte” with “the.” This behavior causes problems when your misspelling resembles a word different from what you had intended; for example, typing “expresso” instead of “espresso” might lead, instead, to the spell-checked word “express.” Spell-check also cannot consistently detect words that are spelled correctly but used incorrectly, such as an incorrect use of “their” versus “there.”

Proper Nouns

A spell-check program might recognize some, but not all, proper nouns, abbreviations or technical terms, and may try to change such words. You can add words to a custom dictionary to help this behavior in many spell-check programs, but you will need to manually add every word you use, including variations: if you add “Brumhilda” as a proper name, you will also need to add “Brumhilda’s." Once you have added these proper nouns, a spell-check program considers them correctly spelled in all cases, which may lead to more spelling mistakes accidentally checked as correct.

Complex Sentences

Like spell-check, grammar-check software uses a limited set of rules and definitions when checking sentence structure. Complex sentences, which contain multiple clauses or compound parts, may confuse a grammar-check program and cause it to ignore a run-on sentence, or demand a semicolon where none is required.

Context and Meaning

Spell-check and grammar-check do not check the meaning of a word or sentence in context. These programs, for example, recognize no problem in the sentence “The fiddle jumped orange under three planets blindly,” whether or not the sentence is meaningless nonsense. Similarly, spell- and grammar-check will not remove negative words such as “not” or “no” even if their use alters your sentence to mean the opposite of what you intended.


Spell-check and grammar-check programs, even when they work correctly, do not teach spelling and grammar concepts. As a result, those who rely too much on such software may struggle to use correct spelling and grammar away from the computer. Thirty-nine percent of respondents to a 2005 survey of British adults by ICM Research said they use spell-checkers all or most of the time, and about the same percentage could not identify the correct spellings of words such as “definitely,” “separately” or “necessary.”

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