What is Brazilian Jiu-Jitsu?
From Wikipedia, "Brazilian Jiu-Jitsu (BJJ) is a martial art and combat sport that focuses on grappling and especially ground fighting with the goal of gaining a dominant position and using joint-locks and chokeholds to force an opponent to submit."
A detailed description and history can be found here.
Am I too old/young to start?
Kids as young as 4 years old can participate in kids classes and there's no upper limit to age. As with any strenuous activity, check first with your doctor if you're unsure.
Do I have to compete?
Competition is a great way to test your progress, but it is not required.