There are several different Cryptocurrency exchanges active today, and each one has their own market structure and exchange rates for any trades that occur. Although many exchanges may trade the same coins (like Bitcoin), each one is a separate market and trades cannot occur directly from one exchange to another.
Generally, there are 3 different categories for identifying a Cryptocurrency exchange:
1. Fiat to Crypto
These exchanges accept Fiat money, such as the US Dollar or the Japanese Yen, in exchange for an equally valued amount in a Cryptocurrency, like Bitcoin. The reverse is also true. You can sell your Cryptocurrency at these exchanges for cash. This type of exchange is your starting point. If you wanted to jump in and purchase any coin or altcoin, you will need to sign up and make a purchase using a Fiat to Crypto exchange.
2. Crypto to Crypto
These exchanges deal only in Cryptocurrency; they do not accept fiat currency at all. These types of exchanges are where most of the trading traffic occurs, trading in and out of various coins and altcoins for both long term and short term investments. If you want to convert your coin to cash, you must first transfer it to an exchange that deals in fiat82 currency.
3. Mobile Exchanges
These are similar to the Fiat to Crypto exchanges, but they are a mobile app version of an exchange. Some of these mobile exchanges may have both a mobile exchange and a web-based exchange, and both would server the same purpose. Others exist only as a mobile platform, and are actually separate exchanges with their own prices. Depending on the app they could be either a Fiat to Crypto exchange, a Crypto to Crypto exchange, or even both.
Each type of exchange serves its own purpose, and you will likely encounter several of each if you decide to invest in Cryptocurrency yourself. Now you understand what to look for when you decide to take the first step.