Can someone please explain to me how twitter works?

I’m not an expert at social media. I do have a facebook and myspace page, but I hardly use them other than to keep in touch with a couple of friends in california and utah. I glance at twitter now and again. I cannot figure it out. It looks like gibberish to me. I’m sorry if anyone is offended. I don’t get it.
I don’t want a twitter, so pretty please don’t suggest I sign up and find out. Just in case someone does suggest that. I know this does sound a bit weird being that I don’t want one, but I want to know what it is that I don’t want. An insider explination, maybe?