It is common knowledge that we have log-in credentials on our systems (e.g., 60Mail) for security reasons: only someone with the correct combination of user name and password can log into the account. However, the log-in credentials are only one part of keeping systems secure; another part of security is to keep your log-in credentials to yourself so that no one else can use them to enter the system. A large part of keeping systems secure, though, is logging off of the system every time you are finished using it.
I've heard an argument that closing the browser window is logging off. Sadly, this is not true. It is quite easy for someone to back their way into the system after you've closed the window. This is why it is important, from a security standpoint, to always log off systems before closing the browser window.
Another reason to always log off of a system when you are finished is to keep the system running efficiently. For example, about a year ago, Infinite Campus was running quite slowly, sometimes taking nearly a minute to log into the system! This slowdown was caused by so many users failing to log off Infinite Campus before closing their browser window. To get a little technical, what happens is that the system still thinks that you are logged in; when you log back in fifteen minutes later, the system has you as logged into both sessions! Each non-logged-off account slows the system.
What it all comes to is that you should always log off a system before you move on. From a security standpoint, a good habit to start is to log off all systems before stepping away from your desk.
Do you have any log off tips to share?