following the hackernoon for full node btc, https://hackernoon.com/a-complete-beginners-guide-to-installing-a-bitcoin-full-node-on-linux-2018-edition-cb8e384479ea i have some small questions, is there's any control for any service on that wallet ? the developers of it ? is that's the way the online exchanges and ledgers create our online wallets and their offline wallets or there's still a deeper way? after making getnewaddress, how can i create/view its private key? from the bitcoin-qt setting>encrypt wallet, what is it about exactly ? is that creating a password for the whole wallet to open it on other pc, or creates custom private key, or 12 words like blockchain.com? if its just a password for the wallet on the pc or another pc usage where can i get the private key for every getnewaddress? also how can i create 12 words that can work on http://blockchain.com when i enter them ? or it cant be as long as this 12 not from blockchain.com directly ? last and not least i didnt find any online documentation that includes all bitcoinq / bitcoin-cli command lines with their explanations and usage, do you have any link including that ?
Bitcoin Core is the name of the software you are referring to, and it is the software that runs Bitcoin. Computers that run Bitcoin Core are usually called nodes on the Bitcoin network. It is open source, and there are hundreds of developers around the world that have and are contributing to it over the last 10+ years.
The software can be run by anyone, and so the wallet that is included with the software must be secured by you. Online exchanges may or may not use Bitcoin Core, but likely have their own wallet implementation. You do not need to run your own node to transact in bitcoin, the wallet software will submit transactions to a node, however.
To create and view a private key for an address in bitcoin core, use:
$ bitcoin-cli getnewaddress <your new address> $ bitcoin-cli dumpprivkey <your new address> <your private key in WIF format>
Encrypting your wallet just makes it so if someone opens your Bitcoin node, they must have your password in order to be able to spend your bitcoin. It is highly recommended to do so. This password is unrelated to the private keys for your bitcoin addresses. The 12 word mnemonics you are referring to is not implemented in Bitcoin Core, and not generally recommended.
Docs for the RPC commands can be found here: https://bitcoincore.org/en/doc/0.18.0/