I've never really worked on cars aside from changing a flat. Ive always wondered, maybe pixacar can help me out, why do you need jack stands? What's wrong with just using the jack?

This! Jeff nailed it on the head here. The risk is just too high to work on a car without stands. I've sold too many new jacks and heard too many stories about scissor jacks that just compressed without warning

T Hugger. About the only work you want to do when on a jack is change your tire, anything else and it's advisable to get it up on stands ASAP. Although its less of an issue with an aftermarket hydraulc jack, you're taking your life into your hands if you decide to crawl under a 2,000 lb machine held up by the scissor jack thats stored in your trunk. These things are notorious for being poorly maintained, and I've heard numerous stories of them just collapsing for seemingly no reason. Add in any extra rocking caused by torquing on a bolt while under the chassis and it could tip right over. Long story short, jack stands offer some extra peace of mind that you'll survive a simple oil change...