Apt-key add

1. What does apt-key add do?
2. Where is apt-key?

What does apt-key add do?

apt-key is used to manage the list of keys used by apt to authenticate packages. Packages which have been authenticated using these keys are considered trusted. Use of apt-key is deprecated, except for the use of apt-key del in maintainer scripts to remove existing keys from the main keyring.

Where is apt-key?

apt-key is a program that is used to manage a keyring of OpenPGP keys for secure apt. The keyring is kept in the file /etc/apt/trusted.