Changing a user's password in Linux is a crucial aspect of maintaining cyber security. It is important to regularly update passwords to enhance the security of your system and prevent unauthorized access. Here is a step-by-step guide to change a user's password in Linux:

1. Log in to the Linux system using the user account for which you want to change the password.
2. Open a terminal window.
3. Enter the command passwd and press Enter.
4. Follow the prompts to enter the current password and set a new password.
5. Once the password has been successfully changed, log out of the system and log back in to test the new password.

It is recommended to use strong and unique passwords to enhance the security of your system. Additionally, consider using a password manager to securely store and manage all your passwords.