Roundcube is an open-source webmail client that enables users to access and manage their emails through a web browser. Written in PHP, it supports IMAP and SMTP protocols, making it compatible with most email servers. Roundcube is known for its user-friendly interface, customizable features, and support for plugins, allowing organizations to tailor it to their needs. Security features include encrypted connections and robust authentication methods. It is widely adopted by businesses, educational institutions, and service providers to offer secure, browser-based email access without relying on proprietary solutions.