Glossary · Ledger
Ada.
The native currency of Cardano, named after Ada Lovelace.
In depth
Ada is the unit users see; it is the fee currency, the staking currency, and the default value carried in every UTxO. Behind the scenes the protocol works in lovelace, the smallest indivisible unit (1 ada = 1,000,000 lovelace).
Example
Sending "10 ada" to a friend is actually moving 10,000,000 lovelace on the ledger.