user323: In rippled's API, for example in account_info, we can see that ledger_hash and ledger_index are different from one another. ledger_hash is just a hash of the ledger. However, in this graphic we can see that ledger_index also looks like a hash of the ledger. There doesn't appear to be an entry for ledger_index in the Wiki, so what is the difference between those two?

user85: The ledger_index is the 256-bit index of a particular entry in the ledger. The ledger's state tree is a hash tree of index/value pairs. Each index is a 256-bit hash of some kind of locator. If the entry is, say, an account root node, the index is a hash of the 160-bit account ID. If the entry is, say, a ripple balance node, the index is a hash of the two accounts the balance is between and the currency identifier.
The ledger_hash is the 256-bit hash of the ledger header, which effectively acts as a hash of the entire ledger.

323: <p>In rippled's API, for example in <a href="https://ripple.com/wiki/JSON_Messages#account_info" rel="nofollow"><code>account_info</code></a>, we can see that <code>ledger_hash</code> and <code>ledger_index</code> are different from one another. <a href="https://ripple.com/wiki/JSON_API#ledger" rel="nofollow"><code>ledger_hash</code></a> is just a hash of the ledger. However, <a href="https://ripple.com/wiki/File%3aLedger_entry.png" rel="nofollow">in this graphic</a> we can see that <code>ledger_index</code> also looks like a hash of the ledger. There doesn't appear to be <a href="https://ripple.com/wiki/JSON_API#ledger_index" rel="nofollow">an entry for <code>ledger_index</code></a> in the Wiki, so what is the difference between those two?</p>
 85: <p>The <code>ledger_index</code> is the 256-bit index of a particular entry in the ledger. The ledger's state tree is a hash tree of index/value pairs. Each index is a 256-bit hash of some kind of locator. If the entry is, say, an account root node, the index is a hash of the 160-bit account ID. If the entry is, say, a ripple balance node, the index is a hash of the two accounts the balance is between and the currency identifier.</p>

<p>The <code>ledger_hash</code> is the 256-bit hash of the ledger header, which effectively acts as a hash of the entire ledger.</p>
