What is Star Wars™: The Old Republic™?
Star Wars: The Old Republic represents a new approach to online entertainment, featuring immersive storytelling, dynamic combat, and groundbreaking companion characters. The game takes place in the Star Wars™ galaxy approximately three hundred years after the events of Star Wars™: Knights of the Old Republic™.
Is this a MMO?
Yes, Star Wars: The Old Republic is a MMO, or “massively multiplayer online game”. Star Wars: The Old Republic will allow thousands of players to explore, adventure, and fight in a single game sessio
Can I play alone?
While there are some tasks that cannot be completed without the cooperation of others, the majority of the game can be accomplished by playing alone.
source: http://www.swtor.com/info/faq