Being in escrow is a contractual arrangement in which a third party (the stakeholder or escrow agent) receives and disburses money or property for the primary transacting parties, most generally, used with plentiful terms that conduct the rightful actions that follow.

Of course, you can use an escrow system outside bitcointalk. The methods are not so different than here. There are platforms such as Setescrow, Bitspend, Bitraded,...
You find a seller, create a transaction and send the money to the middleman (the website). The seller sends you the product, and once you receive the product, the seller is paid.
More or less they all work like this.