I'm autistic and I'll try to answer this for you, but try reading writing by other autistics for even more information. The autistics.org library is a good place to start. (I've used this answer before for the same question, so you may have seen it around Yahoo Answers in the past.) I use "we" and "us" to refer to the others in the autistic community and me. As far as I know, you aren't autistic.
Being autistic means that one has a neurological configuration different from the norm (those of us in the autistic community call non-autistics neurotypicals or NTs). It doesn't mean that one is wired defectively, just differently.
Our senses are different from NT senses: we tend to be either hypo- or hyper- sensitive to sensory stimuli of different sorts, have an increased incidence of synesthesia (a crossing between senses, to use an example from my experience, the ring of a telephone looks like a red spiraling corkscrew), have difficulty parsing speech (central auditory processing disorder), hear pitches that most people can't, and have difficulty reading text because of various visual processing issues collectively known as Irlen Syndrome. (Those aren't all of the sensory oddities autistics can have, just a few of the most common.) Some of our sensory sensitivities can put us at a disadvantage in a society designed for NTs - for example, many of us can see fluorescent flicker, which can result in anything from minor irritation, to headaches, to falling asleep. We do something called stimming, which includes things like flapping our hands, rocking back and forth, listening to the same piece of music repeatedly, and jumping up and down. This allows us to deal with sensory stimuli so that we don't become overloaded, and also lets us get the extra stimulation we may need. Lots of NTs try to stop us from stimming, but while bigots may dislike it, it's necessary for us to function in this world.
Most NTs and many autistics think that being autistic means that one has poor social skills and lacks empathy. In reality, we have autistic social skills and so have trouble interacting with NTs, but are usually just fine with other autistics. While NT social interaction generally takes the form of intrusive give and take interactions, we do better in parallel. We can be successful with NTs, so long as they are willing to do their half of the work to communicate with us, and we can have trouble interacting with other autistics if they have been trained to pretend to be NT or if we have not been allowed opportunities to interact with our own kind, but as a general rule we're better at interacting with other autistics, just as NTs are better at interacting with other NTs. We're also just fine at empathizing with other autistics, and no more lacking in empathy than neurotypicals. Most normal-brained people have difficulty empathizing with autistics. That's why they bully us, why they think that a particular therapy (ABA) that invalidates who we are and tries to replace us with a neurotypical person is helpful, and why they so often excuse the murder of autistics. (Not saying that all neurotypicals are like that, just that many are.)
We also tend to have 1-3 very intense interests, called perseverations. Mine is autism, specifically autistic advocacy, if you couldn't tell already. *g* These are a good thing, and we need to have time to focus on these interests. Monologuing on them isn't bad, in fact, it's one of the parts of natural autistic interaction. If one can't do that, though, it doesn't mean that they're non-autistic. I'm the same way with sharing my interests through speech, I learned to hide them from the time I was about 8 years old. I just don't consider that a good thing, since I would like to be able to discuss my perseverations in real life and not just online.
Oh, and we tend to have difficulties with spoken communication as well, though some of us are eventually fine with it. We're almost always better with text than with speech and usually have trouble with telephones. We have trouble with the figurative language that NTs use, often have trouble with slang, are straightforward in our words, and are often echolalic, meaning that we repeat things that we've heard over and over again.
So far, it seems that autism is genetic - our parents tend to have autistic traits themselves, and we usually have relatives on the autistic spectrum. Autism is not mercury poisoning, and not food allergies. We are more prone to things like allergies than NTs, and we may act differently when those allergies are treated, but we're still just as autistic as we were.
Also, I highly recommend reading all the way through www.gettingthetruthout.org and reading some of the entries in ballastexistenz.autistics.org. You'll both get more information on autism and learn that autistics, even those designated "low-functioning" (I don't believe that functioning levels are useful myself) don't necessarily want to be cured.