Buying on an exchange
The most common way is a regulated exchange or broker. You will be asked for identity documents: this is KYC, know your customer, required by law in most countries. Your purchases are then linked to your identity.
Buying from a person
Peer to peer marketplaces connect buyers and sellers directly. They can offer more privacy, but require more care: use platforms with escrow and reputation, and never pay outside them.
Earning bitcoin
You can also be paid in bitcoin for work, sell goods for it, or receive tips. Earning in sats is how many people start.
Little and often
The price of bitcoin moves a lot, sometimes 20% in a week. Many people buy a fixed amount at regular intervals, whatever the price. This is called dollar cost averaging, or DCA, and it removes the stress of choosing the right moment.
Then withdraw
Once bought, withdraw your bitcoin to a wallet you control. Remember chapter 3: an exchange balance is a promise, not bitcoin.