Replit is a cloud-based, AI-integrated software development platform that allows users to write, run, and deploy code directly in a web browser, eliminating the need for local setup. It features a powerful AI agent that can build, test, and deploy full-stack applications from simple natural language prompts, making it accessible for beginners while providing robust tools for professionals. The "Replit Agent" can create applications from text prompts, generate code, and handle debugging, database setup, and deployment.