The Return to Player (RTP) percentage indicates how much a slot machine pays back over time

https://www.tumblr.com/infinitegunslingertotem/786575908125425664/online-pokies-myths-debunked-what-each-and-every

The Return to Player (RTP) percent exhibits how much a slot system pays to come back through the years, serving to gamers determine games with more advantageous odds.