Merging images is a very good idea when you’re working with lots of layers (like when you’re designing a blog header or button).
Merging allows you to work on one layer and merge all the images together, and then continue to add more layers and images without accidentally moving around (and messing up) the images in the back.
For example, text can be really difficult to move around and resize etc. when you’ve got it on top of another image. Because the text is small, you usually end up grabbing (and moving) the image behind it, which can be frustrating.
Caution: make sure all the layers you’re merging are exactly where you want them to be! You cannot move them around after they’re merged!
HOW TO MERGE:
|THIS IS THE MERGE BUTTON BLOWN UP SO YOU CAN SEE IT|
This is a great idea if you have a standard background you've created and you want to use it more than once. After you merge it, just save it and name it something you will remember to look for each time you are creating an image.
ANOTHER COOL THING ABOUT MERGING:
If you are designing a button or banner and you have elements that are hanging off the edge of your workspace, when you merge, the edges will be cleaned up for you. I noticed this especially if I added partial ribbons or shapes, and then wanted to put a frame around it...there would be funny bits hanging off the edge. Merge solved it instantly!
For more help straight from the Monkey's mouth, click on the PicMonkey Help Center.