Linux Mint is a (partly) community-maintained distribution, supported by donations and advertisements. Their flagship product is based on Ubuntu, but they also provide a “Linux Mint Debian Edition” variant that evolves continuously (as it's based on Debian Testing). In both cases, the initial installation involves booting a LiveDVD.
The distribution aims at simplifying access to advanced technologies, and provides specific graphical user interfaces on top of the usual software. For instance, even though Linux Mint relies on GNOME, it provides a different menu system; similarly, the package management interface, although based on APT, provides a specific interface with an evaluation of the risk from each package update.
Linux Mint includes a large amount of proprietary software to improve the experience of users who might need those. For example: Adobe Flash and multimedia codecs.