Amphetamine is a simple Mac application designed to help you prevent your computer from going to sleep mode. This program overrides energy saving settings which are defined in the System Preferences panel and keeps your Mac awake for any amount of time you like.
The utility lives on your Menu Bar from where you can change the way it operates on your Mac. It allows you to define your own global hotkeys for enabling or disabling a certain profile (for example, keep Mac awake for 10 minutes), shows you the amount of time you have left until the app stops preventing your computer from going to sleep mode, displays notifications, etc.
The Indefinitely option is more of a permanent solution for keeping your Mac awake; this feature comes in handy if you want to prevent your computer from going to sleep mode at all times. You can use this option if you download a large file and you're not sure how long it will take to fetch it from the Web.
Another important advantage is that Amphetamine can also keep your display awake and prevent your default screensaver from running.
To conclude, this program proves to be a smart addition to your collection of Mac programs. It's simple to use, efficient, and free.