Why the Gradient Tool?
Gradient tool’s main job is to create transition between two or more colors
Use it to create shadows or improve a boring background.
Gradients can make a design or graphic more interesting, add spice, create illusion of depth or a shiny effect when you use the type tool.
You can make your effects very subtle or make something really pop using multiple gradients.
You can create crazy effects and can turn these into pleasant backgrounds. Here’s a tutorial from Dave Cross. You have to experiment because it’s hard to predict final result. After Dave Cross has done this part I’ll describe, he adds blurs to create a more subtle effect.
1. Create a blank white new document (New > Custom> about 8.5 X 11 inch and 240 ppi). Fill this new document with white (Edit > Fill > white).
2. Duplicate the background by clicking on Ctrl/Cmd J to add a new layer above your new document.
3. Select your new layer & then select gradient tool. After you’ve selected gradient tool, go to top tool bar& pick one of the five gradient tool shapes and pick a color combination using the drop down to the left of the five gradient tool shapes. You can use PS’s color combos or make your own.
4. Change ‘Mode’ on top tool bar to ‘DIFFERENCE’. If you don’t change it, by default, says ‘normal’, you won’t get the weird effect.
5. With any one of the five gradient shapes, start drawing lines in any direction. Do one line (gradient) after another in any direction. Click & draw line (click, draw, click, draw). You’ll end up with something weird. It seems that the colors pattern switches from light to dark and back with each line/click you make. If you reach one you like, you can save it or, do like Dave Cross, and turn it into smart object and then add filter> Blur > gaussian blur or other filters.
These are just a few the bizarre creations you can make:
Linear light and hard light (rather than difference) also create some interesting effects, the best seems to be with difference.