I saw a post on the anime Facebook page that season 2 was confirmed. However, I can't remember how long ago that was. (The post was really just an image with white text saying Season 2 Confirmed).
I know that sometimes anime seasons go for 20+ episode and sometimes they go for half that yet have a second season that goes up to episode 20+. And since the 25 episodes of Sword Art Online have covers 2 games, I am wondering, is season 1 all 25 episodes or is the 25 episode actually 2 seasons (each season being a different game)?
There is the Aincrad arc, which spans the first 14 episodes and then there is the Alfheim Online which follows and makes up the remaining episodes to 25. These all aired sequentially, with no real "break" from the studio.
ACTUALLY, in order to properly answer the posters question, it goes like this:
the JAP version of SAO had 2 seasons containing exactly 55 episodes (25 in season 1 and 30 in season 2), but for the NA dubbed version, all 55 eps were condensed down to 25 only for North American audiences.
THEN, there is "Sword Art Online 2", which, in Japan, also ran for 1 season containing 24 episodes...and this, too has been dubbed for NA and, somehow, is 25 dubbed episodes for North American audiences. (1 more than Japan this time)
ALSO, there was a "special" episode that aired xmas of 2013 titled "Sword Art Online Extra Edition", which is 101 mins long so is actually more of a movie than an episode
ALSO, there is a "Sword Art Online Offline 1 & 2", which were companion series developed for the special edition Blu-Ray versions of SAO
and last, but definitely not least we have the movie that came out in 2017, "Sword Art Online The Movie Ordinal Scale"...and if you're a fan like myself, trust me, you NEED to see that movie!!