Discord Nitro is a subscription service offered by Discord that provides users with various enhanced features to improve their experience on the platform. Key features include higher quality video streaming, animated avatars, the ability to use custom and animated emojis across different servers, a larger upload limit, server boosts that enhance server settings, and other personalization options. Nitro subscribers also enjoy perks such as the ability to join more servers and participate in exclusive events or promotions organized by Discord.