An address is usually the only identifier anyone has, so the address page is the view most people reach first on any explorer. This page indexes the two address-related views covered here; neither displays live chain data.
The two views
Reading an address page
Balance, full transaction history, and whether the address is controlled by keys or is a smart contract — plus the four checks worth running before treating one as what it appears to be, and the things an address page genuinely cannot tell you.
Reading an accounts list
The chain-wide ranking of addresses by balance, why its top entries are usually exchanges and contracts rather than individuals, and why address count is not user count.
For what an address actually identifies, see what bitcoin actually looks like.