Where do you buy and sell altcoins(or Bitcoins)?

[Agent203]

Which website has the largest choices of altcoins where I can buy and sell altcoins? And when you sell an altcoin, are you selling it back to the website or is someone ( a real person ) buying the coins? As in it can take some time for someone to buy the coin ( And if so how long does it usually take for someone to buy an altcoin from you?)... Sorry I'm new to this. Because I have heard about a couple websites(exchanges) but they are all asking for bank account information!!! Any safe exchanges to trust with a lot of altcoins to choose from? Thank you.