Answer:
The answer to this question is "Password".
Explanation:
In computer science, any User's computer and networks and server is secured with the password to access all we use the password. for example, if we want to access any WiFi system or any User's computer. Then we will insert the password. If the password is wrong so we can't access the WiFi system or User's computer. similarly, If we want to access any server so we must know about the password. Then we use the server and change it's setting.
So the password is the primary means of authentication for all User's.