Your Mac's operating system features a built-in spell checker you can use to find and correct spelling and grammar mistakes. This tool works in many applications that involve typing and don't have their own version of it, including browser, mail and chat programs. When the spell checker is active, incorrectly-spelled words will be underlined in red, while grammar mistakes will be underlined in green. You can also set the tool to check spelling while you type and, optionally, fix any mistakes automatically.
Open the application in which you would like to check spelling and grammar and, if necessary, open a document.
Select a word, click "Edit," select "Spelling and Grammar" and click "Show Spelling and Grammar" to check the spelling of a single word.
Click "Edit," select "Spelling and Grammar" and click "Check Document Now" to check an entire document for mistakes. Doing this highlights the first mistake found in your document. Hold "Ctrl" and click a mistake to see suggested spellings and other options; press "Command-;" to move to the next mistake.
Click "Edit" and select "Spelling and Grammar." If the "Check Grammar With Spelling" option does not have a check mark next to it, click it to ensure the tool checks for grammar mistakes as well as spelling ones.
Click "Edit," select "Spelling and Grammar" and click "Check Spelling While Typing" to be alerted to mistakes immediately. If you want the tool to automatically correct mistakes, click "Edit," select "Spelling and Grammar" and click "Correct Spelling Automatically."
Depending on the application you are using, the menu may be called simply "Spelling" instead of "Spelling and Grammar."
Even if the spell check tool finds no mistakes, it doesn't necessarily mean your text is free of them. If you type "strait" instead of "straight," for example, the tool won't catch it. Always check the text for mistakes yourself to ensure everything is as it should be.