What is Ubuntu sever edition ?

Ubuntu is a complete Linux-based operating system containing the very best free and open source software applications you need to work and play. With Ubuntu you can surf the web, read email, create documents, presentations and spreadsheets, edit images and more.It is community developed. You can interact with the Ubuntu community including developers, translators and technical support activists through our mailing lists and IRC channel.

It is named after the Southern African ethical ideology Ubuntu ("humanity towards others") and is distributed as free and open source software with additional proprietary software available.