Cilantro can regrow leaves throughout the season.
When harvesting cilantro, cut larger leaf stems about an inch from the base. Leave the inner buds to keep the plant healthy and produce delicious cilantro for a continuous harvest.
Seeds from the cilantro plant can be dried and saved to plant again next season.

Yes, after cilantro goes to seed, or bolts, the plant is still edible. The flavor, however, becomes more bitter.
Bolting can happen for many reasons, but most commonly from too much heat or sun exposure. When this occurs, the plant focuses its energy towards flowering instead causing the change in the leaf flavor.
The leaves are still completely edible as well as the flowers the cilantro produces.

Coriander is the name for the dry seeds of the cilantro plant.
Cilantro is known for its distinct flavor, as well as its tasty coriander seeds. In many regions outside the US, the cilantro plant is referred to as a coriander plant and the seeds as coriander seeds.

Coriander seeds can be harvested from the top of the cilantro plant after it goes to seed.
The seeds are small round pods sitting loosely on the stem when ready to be harvested. Cut the seed head off once it's mostly brown. Hang upside down inside a small paper bag to dry. Use a garden tool or rub the seeds to remove the pods.