Red underlines mean that Grammarly has spotted a mistake in your writing. You’ll see one if you misspell something. (See what we did there?) You’ll also see an underline if you misuse a punctuation mark. If you’re worried about typos or grammatical errors that could affect your credibility, Grammarly will help you fix those too. Click any of Grammarly’s suggested corrections to apply them to your text, or open a brief explanation to learn more about the error and how to fix it.

But there’s more to good writing than spelling, punctuation, and grammar. (Sorry, couldn’t resist.)
Brilliant sentences are clear and concise.
Blue underlines indicate that Grammarly has spotted an unnecessarily wordy sentence. Grammarly scores each text based on how clear it will be for your readers and guides you to revise it effortlessly. After all, some sentences are grammatically correct but still awkward and hard to follow. Sometimes you can improve a sentence by eliminating unnecessary words.

If you want even more feedback on your writing, check out Grammarly Premium. You’ll be able to capture all kinds of additional issues. For example, fragments and classical word-choice mistakes. You’ll see suggestions that make your writing sound more confident, polite, and engaging. You’ll even get vocabulary enhancements for bland or bland.