An orphan block is a correctly or incorrectly formed block that the network ultimately rejected and did not include in the main chain. It does not make it into the blockchain's overall transaction history.

KYC/AML is a set of rules under which exchanges and exchange services are obliged to identify customers and counter money laundering. Usually the procedure includes verifying identity by documents.

The Bitcoin Price Index (BPI) is an averaged indicator of the value of bitcoin, calculated from the data of several major exchanges. It helps to assess the market price without being tied to a single venue.

An output is the part of a Bitcoin transaction that sets the recipient's address and the transfer amount. A single transaction can have several outputs at once: for different recipients and to return change to the sender.

An OTC exchange is a venue where participants make deals directly with one another, without placing orders in the shared order book of a centralized exchange. The format is in demand for large volumes.