As @achow101 said, there is no website of the blockchain. Here's a crass overview.

Block explorers give you information about blocks, that contain transactions.

You can uniquely identify a block by it's block hash (Not transmitted between nodes) that is a double SHA256 hash of the block header.

The block header is an 80 byte field that is a concatenation of information in a block, namely - Version, previous block hash, merkle root (Hierarchical hash of transaction hashes - broadly), timestamp, difficulty and nonce.

Traditionally, legacy bitcoin addresses are encoded by computing RIPEMD160(SHA256(Public Key)) and encoding with Base58Check. Newer form addresses (Segwit & Bech32) use different encoding schemes.

Standard bitcoin scripts use DER encoded signatures not base64.