Paradise

ok so im pretty new to MTA, i used to code and do stuff on SA-MP but i decided to come to MTA because it is awesome. The synch is so good and barely any lag. Anyways i was looking at the resources page and my question is theres some resources that only work with nightly builds, i know its a nooby question but what is nightly builds? and what are the difference between mta and nightly builds?