You and your colleagues may login as the administrator to perform administrative work. So you all know the same password. This is really a poor practice. Why? If one of you leaves the company, for security you will have to change the password. If you have 30 such administrator accounts (e.g., OS,  routers, DBMS, ...), then you'll have a lot of work to do and a lot of new passwords to memorize!

A much better way is to use a program called "sudo" (available for Linux and Windows). It works like this: You disable the administrator account and each of you will use a separate ordinary user account. No one knows the administrator password. You configure sudo to recognize these ordinary user accounts. When any of you needs to perform administrative work, you can ask sudo to launch a command prompt or an EXE as the administrator (e.g., "sudo su"). Recognizing the user accuont, sudo will do as told without you entering any password. To trade convenience for better security, you can configure sudo to prompt you for your ordinary account's password. This way, any of you can become the administrator without sharing any common password. If someone leaves, simply delete his ordinary user account and remove it from sudo.

How is sudo different from the runas command in Windows? With runas, you have to enter the administrator account password. With sudo, you only enter your ordinary user account password.

In addition, you can configure sudo to only allow a user to execute a specific command as root. This is useful to delegate simple tasks to junior administrators or power users. For example, at Cyber-Lab, we configure it to allow our part-time technicans to restart our DHCP server using "sudo /etc/init.d/dhcpd restart". 

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