The first Star Wars movie released was - Episode IV - A New Hope - 1977
The next one (sequel) was - Episode V - Empire Strikes Back - 1980
The next one (sequel) was - Episode VI - Return of the Jedi - 1983
After those 3 movies, there was a long break, about 16 years until the next one came out.
The next one (prequel) was - Episode I - Phantom Menace - 1999 - this movie started the series from the beginning.
The next one was - Episode II - Attack of the Clones - 2002
The next one was - Episode III - Revenge of the Sith - 2005
There was another long break, about 10 years. George Lucas was the originator of the first 6 movies and then I think he retired.
The next one was - Episode VII - The Force Awakens - 2015
The next one was - Rogue One which fit in between Episode III and IV to fill in a gap - 2016
The next one was - Episode VIII - The Last Jedi - 2017 - just came out.
I may have missed something. I'm not really a super fan as some but I like them and find them interesting. Maybe some other Star Wars fans will chime in.