Pepper actually refers to several different kinds of plants. Black or white pepper (genus Piper) is a common food spice.
There are different kinds of pepper... There are also a range of pepper that have different levels of "spiciness" or hot sensation: chilli, banana, bell, cayenne and more. It also has the interesting property that some pests may not like it. Allspice is in the pepper family.
- Wikipedia's article on pepper