Ubuntu is a Linux operating system based on Debian that emphasizes simplicity and freedom. It uses the Linux kernel and consists of free software. Ubuntu aims to give users freedom over the software, including accessing source code and modifying or redistributing the software. Major editions include Ubuntu Desktop and Server. It supports common computer architectures and has variants customized for different uses. Popular applications included in Ubuntu are Firefox, LibreOffice, GIMP, and Thunderbird. Ubuntu is a popular choice due to its simplicity, large software repository, active community support, and regular free updates.