Grammarly is an AI-powered writing assistant that works as a browser extension, desktop app, and mobile keyboard to improve writing quality across emails, documents, and messages. It combines real-time grammar checking, tone detection, and generative AI capabilities to help users write with confidence and clarity in any context. Beyond basic proofreading, Grammarly offers advanced features like brand voice consistency, plagiarism detection, and full-sentence rewrites, making it essential for individuals, teams, and businesses looking to produce polished, professional communication wherever they write.