Since that was what was supposed to happen (or not happen) it is obviously an effective way to keep your screen open. We had no way to prove or disprove whether the keystroke happened, but the program lived up to its billing: we left the computer idle for several minutes, which normally would have resulted in the screensaver kicking in, and nothing happened.

The program's description claims it simulated a keystroke once a minute in order to keep our computer from going to sleep. It's pretty much impossible to be confused with such a simple layout. Caffeine basically has only an on/off switch. We enjoyed this program's interface, because it didn't try to overextend itself. It's handy for times when you don't want a screensaver but also don't want to change your desktop settings. Like a strong cup of coffee, the program prevents your screensaver from kicking in without your having to disable the screensaver itself. Caffeine keeps a computer from locking up or falling asleep by regularly simulating keystrokes.