They are exchangers, but you are probably talking about the numbers that you are looking at on coinmarketcap.
Why are there so many markets 7558 versus currency which is 1360?
Let me tell you that this is not the exactly number of exchangers, if you click on there, you will see that there are a lot of lists.
There are more than 30 of bittrex, because those are the pairs in what bitcoin is being tradeable btc/eth btc/us btc/eur btc/gbp, and so on.
The same goes to Bithumb, poloniex, hitbtc, and all theo ther exchanges that are in there.
They are the "pairs" that are listed, not the exactly number of exchanges being trading bitcoin right now.