With snap activated in Photoshop, guides and objects will automatically align with each other. This can be an extremely useful tool. To have guides align with a layer, set that layer to be the active one. Drag the guide in from the ruler bar and it will attach to the outer edges and center points of that layer. To snap a guide to a location that is not the edge of a layer, create a selection with the selection tool. The guide will snap to the outer edges of the selection, which is indicated by the “marching ants”. When dragging a layer near another one, if you are moving slowly, they will snap to each other.

The same snaps will also work with text. Text will align with the edges and centers of objects or guides. Conversely these same objects will snap to the edges and centers of text.