Most people haven't been trading stocks online for long, but that won't be the case for much longer. The only reason it's new to begin with is because the internet is still fairly new. In 1999, a little less than 3 million people traded stocks over the Internet. Now, more than 10 times as many people trade online stocks every day.
Why then have people started doing this? Why is it so well-known? Well, there are several reasons, and when you really think about them, some are good and some aren't as good. Most people say they trade stocks online because they no longer have to give a part of their earnings to brokers in the form of trade fees. This doesn't stop them from having to pay fees for each trade, but it does make it much cheaper to do it yourself with one of the dozens of online day trading companies.
People try to avoid brokers in general for more reasons than just the fees they charge. People are tired of brokers who didn't do well during the recent market drop. People lost a lot of money at their shows, so you can't really blame them. But be careful not to lump all brokers into the group of those who are overpaid and not skilled enough. Many brokers are worth their weight in gold because they know the market so well and have such good instincts. However, this shouldn't be the only reason you want to trade stocks online.
People also quit their jobs to trade on the Internet full time because they think they can do better than at their real job and have more fun doing it. People have a romantic idea of making hundreds of thousands of dollars while sitting in their beautiful home sipping gourmet coffee and checking on their online stock trading portfolios a few times a day. Many people shouldn't do this because they don't know what they're getting into.
If you want to be successful, you need to know how the world's economies work and how the events of the day can affect them. You also need to be good at figuring out how profitable a company could be and so on. The third thing you need is to have steel nerves and not hold on too tightly to the money you are trading with. Many day traders (or people who used to be day traders) will tell you how a bad move cost them tens of thousands of dollars in just a few hours.