The materialization of cryptocurrency is represented by a pair of cryptographic keys: the public key and the private key.
Once you have these keys, you are the one and only owner of your cryptocurrency.
The public key is comparable to your bank account number. It enables you to receive cryptocurrencies. You can share it to third parties without compromising the security of your wallet.
The private key, on the other hand, is strictly personal. It allows you to spend the coins and tokens in your wallet. It must never be divulged, and must be stored in a secure element.