Long-time Mac users probably have different solutions for this problem, but as a newbie, the screen going dim after a certain period of time – without an intuitive way to switch this off – drove me crazy! I wanted to enjoy my slideshow, video, presentation, reading something etc. and suddenly it all went dark. Arggghhh.
So I was delighted when I found Caffeine, a super-light program sitting in your menu bar that prevents your Mac from going to sleep/starting screen savers.
Note that Caffeine doesn’t help if you close the lid – if you want your Mac to stay awake in this case, InsomniaX is your thing – it disables the sleep when closing the lid so you can listen to music/control your Mac with the remote etc.