Cyptocurrency exchanges are platforms through which you can purchase or sell digital currencies for dollars, euros, and pounds, as well as other digital assets. For example, you can sell bitcoins and purchase dollars with the sold bitcoins, or you could exchange bitcoins for ether.
Cyptocurrency exchanges may be brick-and-mortar businesses, exchanging traditional payment methods and digital currencies, or strictly online businesses, exchanging electronically transferred money and digital currencies.
A number of cyptocurrency exchanges operate outside of Western countries, avoiding regulatory oversight and prosecution, but they often accept Western fiat currencies, sometimes maintaining bank accounts in several countries to facilitate deposits in various national currencies.
Some may accept credit card payments, wire transfers or other forms of payment in exchange for digital currencies or cryptocurrencies.
There are private exchanges, which are exclusive and operate by invite only, as well as those available for the public. Local exchanges also exist. Some are easier to use than others are.