When you buy cilantro and don't use it all, put it stem side down in a class of water and lightly cover with a plastic bag and keep in the fridge. It will last several days this way. Some people will do this and leave on the kitchen counter. I can't we have cats that love greens.
Also, cilantro looks very similar to flat leaf parsely, so double check the tag thats wrapped around the bunch you pick up.
As Jo said cilantro is the leaf and coriander is the seed. If you grow cilantro (I do) if its not pinched back it will eventually form seeds (which is coriander). Yummy stuff.
Chipotles are yummy too.
Mama to Conner, Gabrielle & Delaney