Bitcoin Block Explorer is an online block chain browser which displays the contents of individual Bitcoin blocks and transactions and the transaction histories and balances of addresses. It was originally written by theymos, but it is now operated by Liraz Siri.
Each object is displayed in human-readable form, as a web page, and is given a URL. By using hyperlinks, it allows users to switch from seeing one piece of data to a related one, with a single click. Clicking on the hash of an object, will move to the page that displays its data. This way for instance, you can switch from looking at a transaction, to looking at the previous transaction which gave this transaction its inputs. All block data is visible, in human-readable or machine-readable forms, and even some information that is not actually part of blocks.
It is mainly aimed at advanced users who already know what blocks are and what kind of information they contain, but a lot of helpful information is provided in tool-tips. A listing of “strange transactions” is displayed in the main page, along with listings of the latest and largest transactions.