The Terms, in Plain Language
A darknet market assumes you already know the words, and it does not slow down to explain them. This is the short list of the terms you will actually meet, defined without the jargon, so the guides on this site read smoothly. None of these are hard. They are just unfamiliar, and unfamiliar is fixable.
The network words
An onion address is the address of a site on Tor, a long string ending in .onion that only the Tor Browser opens. A mirror is a second onion address pointing at the same service. A circuit is the path your traffic takes through the relays. A new circuit is a fresh path, and it is the fix for a stalled address.
The money words
Escrow is the hold on your funds until you confirm, so the seller cannot take the money and vanish. A deposit is the coins you send to fund the platform wallet. A withdrawal is moving coins to an address you control. A dead drop is a physical delivery to a shared location, with no name or address on the package.
The verification words
A PGP key is a pair of keys, one public and one private, used to encrypt and sign. A fingerprint is the short form of a public key, used to confirm you are looking at the right one. A canary is a short signed message that lists the live addresses. A lookalike is a copy of the storefront, usually one character off, built to catch a deposit.