1) Is there a way to choose my Personnal key (using some sort of algorithme from a pass phrase) ?
- I get that if the passphrase is week, so will my "account".
The technical answer is yes. You can choose your own "account" which is really just a big random number which becomes your "private key". However, it's not a good idea to do this. Humans are not good at being random. It's better to use established, tested wallet software which does this for you. It's important because the security of your account depends on this and safety for your funds is your own responsibility. I recommend using Electrum which can be downloaded here:
https://electrum.org/ Electrum makes wallet management secure and easy
2) People says that adresses are accounts, but also that each adress should only be used once. How is this working ?
An account is really two things: a public key and a private key. From these you can generate a Public Address which looks like this: 1BvBMSEYstWetqTFn5Au4m4GFg7xJaNVN2. You can give anyone your Public Address and they can send funds to it. Funds can be sent to addresses repeatedly, but for better privacy it's recommended to use a new address for each new payment. This makes it harder for anybody to link your payment activity back to your real world identity. Anonymity is another big topic. Wallet software like Electrum manages your "accounts" (your public and private keys) and Addresses.
Lastly, I'd like to try to understand how bitcoin transfers Work. But for that I need some Cheesy.
- Any one would have even the smallest part of Bitcoin (Satochi if I'm not mistaken) to spare ?
- Here is my adress : 1CUtoK6PNcyUjaCPxHTmMAPFP2FWxXNSFn
Be careful asking people to send you money as it's not allowed in many discussion forums. This is because too many people would do it. I understand you're anxious to play with some coins
, I would send you some Satoshis as they're called (which is .00000001 of a Bitcoin) but the network no longer allows such cheap transfers to go through. That's another big topic. To gain free Bitcoins people use "faucets". Just search on Google, but I warn you it make be a hassle. It's usually easier to just buy some.
How does change work ?
- I get that if you pay 1BT with an adress who has 2BT, then you get 2 transactions. 1 to send 1BT to the recipient, but then, you get another adress with the remaining 1BT ? But how do you get the private key of this adress ? As I seem to get : No privateKey, No Money !
If you use wallet software like Electrum you don't need to worry as it's all handled for you, but since you asked I'll explain it. A Bitcoin transaction consists of inputs and outputs. The inputs specify where coins are coming from and the outputs specify where coins are going to. Let's say you have 1 BTC and you want to send me 0.2 BTC. That means your change is 0.8 BTC. I give you my Public Address and you tell your wallet to send my address 0.2 BTC. Your wallet makes two outputs, one to my Public Address for 0.2 BTC and another output for 0.8 to a Change Address you have. Good wallet software will create and manage change addresses for you. When someone looks at the Bitcoin Network they will see the two transactions, but they won't know which address was the Change Address, the payment going back to you (a privacy feature) if you always use different addresses.
Thanks for taking the time to answer all of my noob questions.
You're welcome! Welcome to the Bitcoin and cryptocurrency world!