What Role Does Transaction Confirmation Depth Play in Mitigating the Risk of a Double-Spend?

Transaction confirmation depth is the number of blocks that have been added to the blockchain after the block containing a specific transaction. Each subsequent block makes it exponentially harder and more expensive for an attacker to successfully reverse that transaction via a chain reorganisation.

Exchanges and merchants typically wait for a certain number of confirmations (e.g. 6 for Bitcoin) before considering a transaction final.

A greater confirmation depth significantly increases the economic cost of a successful double-spend, thereby mitigating the risk.