It may be because you need to repeat an object. Sometimes the need arises to create a custom brush in Adobe Photoshop.

No tool is more intuitive than the brush tool.

Once you are comfortable with the brush tool, the other tools seems to fall into place much easier. Mastering the brush tool is the first step to learning and mastering Adobe Photoshop. This is simply because of the versatility of the tools in Photoshop and other digital painting programs. In fact, many traditional artists, especially illustrators, have migrated to the computer. The brush tool in Photoshop can be used to create effects that can resemble actual paintings and drawings. Couple all of the abilities of the brush tool with a digital tablet and you're 'rolling'. You can even make your own brush in Photoshop. You have the ability to change the stroke, the transparency, the color, the texture and many other aspects of the mark. The brush tool is also one of the most versatile tools in the tool palette. The brush tool is the easiest tool to use to make a mark. It seems to me that the most logical place to start for any beginner is with the brush tool. When you are just beginning with Adobe Photoshop, and you aren't sure what you are doing, starting out can be intimidating. Adobe Photoshop, however, is a powerful imaging program that can be used for drawing and painting. When most people think of Adobe Photoshop, they think of photos.

Learn to use photoshop for beginners