…is the maximum time that software can elapse without doing anything before the user thinks something has gone wrong.
I looked this up after trying to move my cable service from one location to another on comcast.com — while ostensibly a helpful service I never actually made it thru the process. I was attempting to do this while eating lunch at my desk and listening to my voicemail. Whenever I submitted or requested information I thought the site was down as it never displayed a processing icon and I simply thought the site was down and hit refresh — multiple times. Now I could have just glanced over at the status bar on the lower left hand corner of the browser, but while eating lunch and checking v-mail this was not something I thought of at the time and I imagine that millions of users actually have no idea where the status bar on a browser sits or what it does. So, after multiple failed attempts I ended up calling the Comcast call-center costing them about $5+ to handle my call. While $5 may not seem like much the fact that such a simple user interface fix cost them real dollars is unfortunate.