Escrow

Escrow is an arrangement where a neutral third party holds the money for a transaction. The buyer pays into escrow, the holder keeps it, and it is released to the seller once delivery is confirmed.

It solves the problem of two strangers transacting. Paying first risks never receiving the goods; shipping first risks never being paid. Escrow places a trusted holder between the two.

It is standard in property transactions, and the secure-payment options on online marketplaces run on the same principle. In the United States, home buyers often keep an escrow account that accumulates tax and insurance monthly.

There is a fee, but on larger sums it earns its keep. Where you cannot verify who you are dealing with, the risk of fraud far outweighs the cost of the service. One caution: fake escrow services are a common scam. Rather than following a link the other party sends you, go to the marketplace's own secure-payment option directly.