I hope that's not a silly question, but...they're the only peppers I know that aren't actually spicy. How do they get the name "pepper" and what about them makes them mild?
"Invented by Wilbur Scoville, the Scoville Heat Index ranks peppers in order from mildest to hottest. It starts with zero being the mildest and goes over 1,000,000 to indicate the hottest peppers. "
"Bell Peppers, which can be red, yellow, green or orange, aren't hot peppers. They are very common sweet peppers. Since this type of pepper has no heat, its Scoville Heat Index is zero. You can cook bell peppers in a variety of different ways, however don’t expect this type of pepper to add spice to your food."
"The terms "bell pepper", "pepper" or in Australia and New Zealand "capsicum", are often used for any of the large bell shaped fruits, regardless of their color."
They're still a type of pepper, just without the heat as other peppers have.
Okay it's a bit ridiculous that I get 2 thumbs down when I provided answers to your questions. Btw I did forget the links, but I used wikipedia and google which aren't exactly the hardest things to use on your own.