owner reveals what kind of thing it is).A base58-encoded 32-byte ed25519 public key — typically 32 to 44 characters using Bitcoin's base58 alphabet (digits and letters, no 0/O/I/l). Wallets, programs, mints, and program-derived addresses (PDAs) all share this format.
Solana addresses are raw base58-encoded public keys. There's no embedded checksum — a single typo produces a different-but-still-valid-looking address. Always copy-paste; never type a Solana address by hand.
Not from the address alone. Wallets are on-curve ed25519 points; programs and PDAs are off-curve. Distinguishing them requires actual ed25519 arithmetic — beyond the scope of a quick validator. The on-chain way is to fetch the account and inspect its owner.
Yes. Solana addresses are network-agnostic — the same public key represents the same identity across mainnet-beta, testnet, and devnet. Whether the account exists on a given network is a separate question.