Proofreading is the process of reviewing the final draft of a piece of writing to ensure consistency and accuracy in grammar, spelling, punctuation, and formatting. It should always be done by a native speaker of the target language.
Proofreading should always be the last step taken before a document is published online, handed in, submitted for a job application, or otherwise shared with its intended audience.
Professional proofreading will help you polish your writing and ensure it is ready for your readers.