As a web designer, you often have to repeat tasks using Photoshop. You may need to resize and save a lot of images, apply the same filters and effects over and over again etc.. This can be tedious and time consuming. As always, if you are repeating a task frequently when using a computer, you are probably doing it wrong as your machine is a lot better and faster than you are! How to make this happen? Photoshop actions!
Let Photoshop do the boring work for you!
Here is a video by Phlearn (Great Youtube channel for Photoshop tutorials) explaining very well how Photoshop actions are setup