Use the PowerPoint spell check and PowerPoint grammar check features to ensure your PowerPoint presentation is free of errors.
With customizable proofing options, PowerPoint gives you the ability to change the way it addresses spelling errors, including automatic spell check and contextual spelling. Contextual spelling—an option that is turned off by default but that can be turned on—can help you find and correct spelling mistakes like the use of too vs. two or there vs. their.
If you've turned off the automatic spell check, you can still run a check by going to the Review tab and clicking the Spelling command.
Modifying any settings in PowerPoint Options—including Proofing—affects all of PowerPoint, not just your current presentation.