First of all, a vegan is a person who doesn't eat or use animal products to the best of their ability, animal products include, meat, fish, leather, gelatin, dairy, eggs, leather, fur, wool and sometimes silk. Some say the difference between vegans and vegetarians is that vegetarians also don't eat dairy, but also dont use products (fur leather animal tested products, etc..) so as far as I know there's no real specific definition, just do whatever the hell you want! Everything you do makes a difference no matter how big or small.