What a block explorer shows

A block explorer is a search page for the public Bitcoin record. Paste in a transaction ID, an address or a block number, and it shows what the chain holds for it. It can't move coins or change anything; it only reads, and anyone can build one.

Live from the chain

Reading a blockLoading live figures…

Block number

…also called the height

Added

…

Transactions inside

…

Fees paid to the miner

…all transactions together

Mined by

…from the block's own tag

Every explorer shows these same facts for this block, because they all read the same record.

See it on satoshis.watch →

Three things you can search for

Transaction ID	A 64-character code, also called a txid or hash, that names one payment. Your wallet or exchange shows it after you send. It is the most exact thing to search for.
Address	Shows every payment in and out of that one address, and what it holds now. Remember that a wallet uses many addresses.
Block	Shows when the block was added, who mined it, and every transaction inside.

A transaction, field by field

Here is the first payment between two people, from block 170, the way an explorer lays it out:

Field	What it shows	Block 170's payment
Transaction ID	The payment's name	f4184fc5…9e16
Inputs	The earlier pieces of bitcoin being spent	One: the 50 bitcoin reward from block 9
Outputs	Where the bitcoin goes now	Two: 10 bitcoin to the receiver, 40 back to the sender as change
Fee	Inputs minus outputs, kept by the miner	Nothing: 50 in, 50 out
Size	Space taken in the block, which sets the fee	275 bytes
Status	Unconfirmed, or the block it is in and its confirmations	Block 170, on 12 January 2009

The fee is never written down as its own line. It is simply what the inputs hold that the outputs don't pay out, and the miner collects it.

An address page

An address page usually shows the balance now, the total ever received and sent, how many transactions touched it, and a list of them, newest first. Many explorers also list its unspent outputs: the separate pieces it holds. Pieces, change and balances explains why those matter.

Explorers often add a dollar value and sometimes a name such as an exchange. Those come from the explorer, not from the chain. The chain itself records amounts, addresses and times, never names.

Unconfirmed, then confirmed

A payment that has been sent but isn't in a block yet shows as unconfirmed or pending. Explorers learn about it from the queue of waiting payments, which each node keeps for itself, so a brand-new payment can appear on one explorer a few seconds before another. Once it is in a block, every explorer agrees. See fees and confirmations.