The idea of a track system is to create a more natural environment for your horses, so theyhave to move about in order to forage. You create tracks using permanent fencing or electric fence stakes and tape to give a track with preferably different surfaces, like pea shingle as well as grass with access to hedgerows where possible. You put your forage feeders for hay etc at one part of the track along with water and the horses need to travel to reach grass or the hay, water etc. I have a system with grass paddocks in the centre that I can open and close off as I choose. I am really pleased with the system. If you Google 'Paradise Paddocks' you will find more information. Some pics below of my system.
The 'track system' is basically a simplified version of Paddock Paradise by Jaime Jackson, which is actually an interesting book to read, based on studies of how wild herds move and aimed at keeping horses more naturally, specifically barefoot, but appropriate for horses that need restricted grass intake, any horses for that matter: