Please see the discussion page on uploading track pictures.
Tracks are the setting in the BTD series where all the action takes place. (Besides in BTD) There are many tracks to choose from. Tracks have varieties, including number of Bloon entrances, appearance, length, and more. Most tracks don't have a specific name.
BTD Tracks
In the original Bloons Tower Defense, there is only one track.
BTD2 Tracks
There are 3 tracks; easy, medium and hard.
BTD3 Tracks
There are 8 tracks in BTD3. The bottom 4 aren't available if you aren't playing on the Ninja Kiwi website.
BTD4 Tracks
In BTD4, there are 7 default tracks and 7 premium tracks.
Bloons TD 4 Expansion Tracks
There are 4 tracks; the beach, the sewer, the monkey temple and the triangle of insanity, as well as the 7 premium tracks in the regular BTD4.