Re: I don't understand..

I got confused the more... God

Thanks anyway

You have a house. You have a key to your house. Your key to your house is owned by the exchange. The exchange gives you the key so you can enter your house. If the exchange disappears your key will disappear with them and you can no longer enter your house.

BUT

Some wallets (mostly offline ones) let you have your own keys owned by you alone and you can use these keys to enter your house any time you want. You can import these keys into other wallets which will let you into your house (coins).

Now apply this example to your coins Wink

Great explanation. I wouldn't do it better. There is nothing to add or take from that. I even cleared up some moments to myself about which I wasn't sure!

Private keys are like your password to your address, you are the only one that can view it. you can read it more here https://github.com/OmniLayer/omniwallet/wiki/Exporting-a-private-key-from-Bitcoin-QT-Bitcoin-core-and-Importing-to-Omniwallet.org . When you want to import your private key you can read here how https://multibit.org/help/v0.5/help_importingPrivateKeys.html
Dont store all your coins in an exchange because 100% of all exchange can anytime disappear or hacked they said.