Every so often I come across a user experience that is most likely a bug but could also possibly be by design. Here’s a good example. I often write myself emails through Gmail to serve as future reminders. Essentially overloading e-mail and leveraging it as a todo list. After sending myself an email from my laptop this evening, I noticed that Gmail told me that I sent the email 3 minutes ago – even though I had just sent the email. After some investigation, I saw that Gmail uses two different data sources to figure out when an email was written and how long ago it was written. Let’s take a look with a sample email: 

As can be seen in the second image above, 7:54 PM is based on the actual and correct time (according to Google’s servers) as to when the email was written. “3 minutes ago” turns out to be based on my computer’s internal clock. This can be easily reproduced by opening up the settings in OS X and changing the computer time to some time different than the correct time.