Why#Bitcoinbelongs to you?

A random number is required to create a bitcoin wallet.

You can come up with a random number from your head, you can get it with a coin (heads/tails), dice, a deck of cards, and in general any way you can think of.

In smartphones, a random number is generated by software + analog signals from the microphone, camera and other sensors of the device.

No internet is needed to generate a random number, so only you will know the random number, so only you will have the right to manage your bitcoins.

Using cryptographic algorithms, a Private Key is created from your random number, and a Public Key is created from the Private Key.

The public key is converted to a bitcoin address that you show to receive bitcoins.

The private key is kept secret and is used to digitally sign transactions where you send bitcoins.

In modern bitcoin wallets, the method of Hierarchical Determination (HD) is used, which can create many Private / Public key pairs from one random number.

In HD wallets, your random number is represented by a seed phrase that only you know and keep secret.