A carbon footprint is a term used to describe our impact on the environment around us, be it through overuse of things like electricity or something as simple as litter. Humanity, as a whole, has a gargantuan carbon footprint, big enough that it's altering the world that we know it and making the environment's future look bleak. To some people, this matters more, while others don't believe the way they live their lives could have that much of an impact on the world. Have you ever thought about your carbon footprint; how you could reduce it, how big it is already?
Naturally, there are many ways in which one could reduce their footprint. Even something as simple as turning off all electrical items when they're not in use could reduce it, or taking a walk to school/work as opposed to burning fossil fuels by using a car. If you're not a fan of exercise, even just getting public transport will reduce the number of cars on the road. Eating organic foods, recycling and reusing, taking showers instead of baths ... those are all things we could use. Do you do any of these, or would you like to start doing so? If not, why?
I also found a little quiz over here for anyone interested in discovering their carbon footprint. Of course, I can't assure 100% accuracy, but it may be able to give you a vague idea of how large it is.