Hello!
There are numerous exchanges online in order to invest or trade bitcoin and alternate(ALT) coins.
I will try to give you some basic and important information as I have long time experience using them.
BITCOIN EXCHANGES:
- Kraken: Very reliable exchange which accepts both FIAT (EUR/USD) currencies and also Bitcoin and Ethereum. Your money is safe in Kraken.
- Bitstamp : Also very safe exchange. Even it was hacked sometime ago, Bitstamp took responsibility and did not run away because of financial lost
- Bitfinex: Reliable exchange where you can use leverage trading. However platform is a bit complicated
- www.btc-e.com : Kind of Shady exchange. It is believed to be located in Eastern Europe.
- Chinese exchanges (Huobi and Okcoin) they have %0 fee policy and Has huge volumes but their website is not design for western people. It is hard to adapt Chinese.
ALTCOIN EXCHANGES
- Poloniex: Started in early 2014. It has proved to be reliable during last 2,5 years from users. Poloniex has 100 Millions of worth of Bitcoin and Altcoins in its cold wallets. Never had problem with them
- Bittrex: Secured altcoin exchange. Problem is there is not huge volume. It has many small coins but trading platform is very nice
I hope this small review gives you some info about this new crypto world!