From the website:

Picli revolves around a constantly changing gallery of quality creative content, created and edited by its users without editorial control. The main page features 2 galleries - the 'Showcase' gallery and the 'Upcoming' gallery.
The Upcoming gallery contains work that has been recently submitted to the website. Users can view these images and vote on which images they like. Picli then automatically works out which are the most popular images at any given time and promotes these into the Showcase gallery.