Heterochromia basically means you have 2 different colours in your one eye, both eyes or both eyes are different colour.
To break it down there are 3 different types of Heterochromia.
Complete - One eye is different from the other. Ex, One blue eye one brown eye.
Sectoral - Is when there are 2 different colours on the same iris. Like a splash or section.
Central - Is when there is a ring of colour around the pupil.
I myself have a Central Heterochromia.
Not the best picture but you can clearly make out my green-ish iris with a red brown ring around my pupil.
Its a really cool type of mutation. Its relatively rare. Something like 10 out of 1000 people will have it.
Just thought I would see if I have any other mutant brothers and sisters out there
Also here are 2 links with some info on Heterochromia :
http://en.wikipedia.org/wiki/Heterochromia_iridum
http://www.environmentalgraffiti.com...people?image=0