Simply put your "Carbon Footprint" is the amount of carbon dioxide emissions created by a person or industry. To further explain it is the amount of carbon dioxide output by yourself, your home, your vehicle, your every day life. There are several sites that can estimate your carbon footprint & offer tips to reduce it.
Why would you want to reduce it you may ask? Well, because the earth can only maintain so much carbon dioxide, we need oxygen to survive, so we want more oxygen & less carbon dioxide, or the earth and it's inhabitants; humans, cannot possibly survive.
Here is a site where you can measure your carbon footprint: http://www.conservation.org/act/live_green/carboncalc/Pages/default.aspx?gclid=CLiwk5qh7KMCFZZM5QodZh0k3w
There are many sites with suggestions & tips to reduce your footprint, I will give you one example: http://www.whatsmycarbonfootprint.com/reduce.htm
Now, this is an interesting site I stumbled upon while doing some research http://www.carbonfootprint.com/ If you have some time check it out!!
Have a wonderful Friday everyone!!