How does dried cilantro relate to fresh?

Coriander, the plant, is the one whose leaves are called cilantro in many regions - the Spanish name for the plant. Of course, in some regions, the leaves are called coriander (or coriander leaves) as well. Coriander, the spice, is indeed the dried fruit/seeds of the plant, commonly sold both whole and ground. The seeds have a very different flavor from the leaves.

As for dried cilantro, the leaves? They're going to be pretty much flavorless compared to fresh cilantro. Cilantro loses its aroma quickly when heated or dried. Obviously there's still something left, or you wouldn't be able to buy dried cilantro, but it's not going to be a striking addition to a dish. If you can get it fresh, it's worth it.

These are the seeds:

These are the leaves of the more common variety (there are many others):

While dried seeds are full of aroma and flavour, dried leaves are not.

BTW, it is VERY easy to grow cilantro (as parsley) in a pot, just use the seeds ...

Instead of drying the cilantro, why not just plant the other half in good potting mix? You won't have to run to the store for fresh then. It grows quickly too!

I have both dry and fresh. The dry doesn't stack up. It has a much less pungent flavour. It's good in a pinch.

It tastes foremost of "generic dried herbs" - the typical hay-like, bitter taste with a note of cilantro. It is mostly sold so people can put a checkmark next to the "cilantro" line in a recipe.

While applications exist and have been mentioned in other answers, it is not a valid substitute for fresh or frozen cilantro (which I heard exists in some places - not here unfortunately, and it does not home freeze well).

I made home made salsa and used dried cilantro in a tin that I bought from the store. I threw the salsa out and gave my dried cilantro in the spice tin away... It was awful awful awful and didnt taste a thing like fresh cilantro. It ruined mmy salsa... never again will I buy it in the grocery store.

Dried cilantro brings a mild herbaceous favor to soups and stews but it is not a substitute for fresh cilantro. If you take the notion of subbing for the fresh stuff off the table, dried cilantro is interesting... I often use both because they bring completely different things to the party.

To make things easier - dried coriander (leaves) looks like dried parsley - that is green.

Coriander seeds are yellowish and therefore the ground version is also grey yellow in color.

The tastes are completely different - the ground seeds have a pungent taste and are not used in salads or cold dishes.

The leaves, whether dry or fresh can be used as is without cooking, e.g. add them to a salad.

I have heard to use twice the dried if the substituting for fresh in a recipe. Joy of Cooking has good substitutes listings including dried for fresh.