Guides in photoshop can be found/used by clicking the ruler either on top or left and drag out to your canvas. These are guides. They can be extremely helpful when designing with a certain layout in mind. As a web designer I use both the normal guides an smart guides when creating a mockup in photoshop.

To activate both if you have not already:

View>Show>Guides
View>Show>Smart Guides

When working with your piece in photoshop there is a quick shortcut to hide the normal guides.

Win: Ctrl+H

And you can bring them back up by doing the same command again.

Another great feature that the normal guides can do for you, is it can make using the marquee tool simple. The marquee tool will snap to the corners/sides of the guide(s). So your not all zoomed into your canvas using the marquee tool to get from corner to corner.

Example:



Now lets move onto the Smart Guides. We have already went over how to activate them. Now lets learn to use them and what purpose they serve for you and your document.

Smart Guides are alittle different and cannot be used by dragging from the ruler tool. Instead they are there when you are moving layers/objects on your document. They will show as pink lines and will align you objects in ways you cannot with the normal guides.

Example:



Now in the example picture above you see the smart guides in action. I went to move the right box down and as I got to the middle of the left box it recognized that object and activated the smart guides telling you that your right object is now perfectly offset with the left object from its middle base.

Both Smart Guides and Normal Guides can save your life when working with pieces that have a structure/layout to them. I hope this guide has helped increase your knowledge in just a couple of many features in Adobe Photoshop and helps you with your future designs.