What is the "others" column when looking at the charts in Reports?

When looking at the Top 10 of a Reports chart, others is made up of everything else not listed.

You can see the Top 9 sites visited by users in a day, while others is there to give us a baseline.

For example if we saw one or two users with a larger percentage than others, we'd probably want to do some investigating as to why that user is pushing more web traffic than a large portion of the organization (relative to total organization size).