that's sorting as well. It's just sorting according to another criteria than the natural one.

let's say you own a restaurant. lots of people are in line to eat at your establishment, but only some of them have ever bothered to tip your staff well. so, as they approach you one by one, and you remember how they've tipped in the past, you decide to offer preferential seating based on this knowledge. so you split the line based on this and queue up those that have tipped well to be given an opportunity to get a seat sooner than those that have not. now you have two lines. your staff is happy. the bums come last. justice, and delicious dinners, are served.