Replit is an online development environment that provides a platform for programming and collaboration. It allows users to write and run code, collaborate on projects, and access a library of open source code. It supports over 50 languages and is ideal for web development, game development, and code collaboration between individuals or teams. It also provides an online editor, compiler and interpreter. With its cloud-based infrastructure, Replit enables quick collaboration, making it a great option for learning and teaching coding.