new question for Ash, Tyler, or Predreg

Since my website is apparently really big - and will get bigger with time as we add 1 - 2 pages and a couple of blogposts each week I'm considering splitting the info and creating 3 separate websites. In mentioning this to various techies online the question has come up about 'multisites'. I have no idea what they are or how they work. I looked in the support communities and was unable to find basic info as to their pros and cons to decide if this is how I want to go.

And, since you have all helped me on other support tickets, the ultimate question is, since I'm not a techie is multisite even a possibility for me?