Shielded Pool

The shielded pool is the collective total of all ZEC held in shielded addresses at any given time. Unlike transparent addresses, transactions within the shielded pool don't reveal the sender, receiver, or amount on the public blockchain — only that a valid, zero-knowledge-proven transaction occurred.

A bigger, more active shielded pool means a larger "anonymity set" — more genuinely similar transactions for any single transaction to blend in with, which strengthens privacy for everyone using it. This is why using shielded addresses is generally encouraged over transparent ones.

Zcash has had multiple shielded pool implementations over time (Sprout, then Sapling, then Orchard), each an upgrade to the underlying cryptography and performance.