Sword Art Online Order?

Am now on episode 19 watching Netflix and I'm confused I know that the Original Series has 3 seasons, but what about SAO 2 and SAO is aging Univerve on itself. Please tell me how to look at the different series?

Sao (1 season)

Sao Gun Gale Online (2 seasons)

Sao Ordinal Scale (film)

Sao Alicization (3 seasons)

Alternative has nothing to do with the main story, so you can just look in between or let out completely.

Thanks man, so in order or?

Yes exactly

Sword Art Online (S1)
Sword Art Online II (S2)
Swort Art Online Ordinal Scale (Film - Canon)
Sword Art Online Alicization (S3 - simulcast at Wakanim)

Gun Gale is just a spin off and not the third season!

https://myanimelist.net/...ime/11757/

https://myanimelist.net/...ime/20021/ (Extra is a 50% repetition of Season 1 and 50% a Side Story)

https://myanimelist.net/...ime/21881/

https://myanimelist.net/...ime/27891/ (Optional Rehearsal of Season 2 Episode 1-14)

https://myanimelist.net/...ime/36475/ (Look for episode 14 after Season 2, but you do not have to look, if it's a spin-off, it's nothing to do with the consequences)

https://myanimelist.net/...ime/31765/
https://myanimelist.net/...ime/36474/

More precisely one can see that on Wikipedia.