What are the main exchanges that are used for trading? I have heard of binance and coinbase, but I wanna know the other options and the benefits of each.
See
https://coinmarketcap.com/exchanges/volume/24-hour/Bitfinex, bitstamp, gdax, are all primarily used for BTC/USD trading, then you have some South korea exchanges, and exchanges such as poloniex, bittrex for most popular altcoins, and sites such as cryptopia for really low volume / unknown altcoins.
Depending on where you're from you might not be able to trade on all of them, which is also partly why there's such a large variety of them.