If you find yourself performing repetitive tasks over and over (and over) in Photoshop, setting up a batch process is the way to go. Basically you ‘record’ your actions and then ‘play’ them on a group of files at once. This can be useful if, for example, you have 500 digital pictures you need to resize.

For a quick guide on how to set this up, check out this page which gives a brief overview of the function and shows how you can create your own batch processes. To see a batch in action, check out this video which shows a demonstration of a group of images being watermarked at once.

In general, the ability to perform batch processes (or macros) is extremely powerful, so if your application offers this feature, take advantage.