My bitcoin wallet doesn't actually contain my bitcoin. What it does is keep my bitcoin address, which keeps track of all my transactions and therefore my balance. This address, a long string of 34 letters and numbers, is also known as my "public key". I don't care that everyone can see this sequence. Every public address / key has a "private key" corresponding 64 letters and numbers. This is private, and it is crucial that you keep it secret and secure. The two keys are related, but there is no way I can find out my private key from my public key.
That is important, because any transaction you issue from my bitcoin address must be & quot; signed & quot; with my private key. To do that, I put my private key and the details of the transaction (how many bitcoins I want to send and to whom) in the bitcoin software on my computer or smartphone.
With this information, the program spits out a digital signature, which is sent to the network for validation.
This transaction can be validated, that is, it can be confirmed that I am the owner of the bitcoin that I am transferring and that I have not yet sent it to someone else, by connecting the signature and my password. ; blica (which everyone knows) in the bitcoin program. This is one of the cool parts of bitcoin: if the signing was done With the private key that corresponds to that public key, the program will validate the transaction, without knowing what the private key is. Very smart.
Then the network confirms that I have not previously spent bitcoin by checking my address history, which it can do because it knows my address (= my public key) and because all transactions are public on the bitcoin book.
Once my transaction has been validated, it is included in a "block", along with a bunch of other transactions.
Each block includes, as part of its data, a hash of the previous block. That is what makes it part of a chain, hence the term & quot; blockchain & quot ;. So if a small part of the previous block was altered, the hash of the current block would have to change (remember that a small change in the input of the hash the function changes the output). So if you want to change something in the previous block, you also have to change something (= the hash) in the current block, because the one that is; currently included is no longer correct. That is very difficult to do, especially since by the time you are halfway there is probably another block on top of the current one. Then you will also have to change that. And so on.
This is what makes Bitcoin practically tamper-proof.