|Blockchains use public-key cryptography, also known as asymmetric cryptography, to verify ownership. Every user creates two keys when he joins the network, a public, and a private key.|
The public key is like an address, in that you give it to anyone who wants to send you money. If a friend wants to send you some cryptocurrency, you will give them your public key.
The private key is like a password, in that it can access your money and spend it, similar to how someone with your email password can log into your account and send emails in your name.
It is important to protect your private keys. If someone gets their hands on your private keys, they can steal your money.
If you would like to learn more you can find an article about Public-Key Cryptography in our Technology section.