The Gradient Tool lets you draw a simple color gradient across layers (pixel layers, fill layers, adjustment layers, live filter layers, layer masks) as well as vector and text content. However, you might want to apply a more complex fill, introducing more than two colors along the gradient path, adjust where each color is positioned and/or control color transitions. You can do this directly on the page using the tool's gradient path.
If you apply a gradient directly to your image's layer you'll destroy the layer content. Instead, apply gradients to a separate pixel, fill, adjustment, filter, mask or vector layer. With Fill layers, your gradient path will additionally remain editable.
With the Gradient Tool selected, select the layer content with a gradient applied and then do any of the following: