Contrast is the value difference between the colors in your art piece. And the value is how bright or dark your colors are next to each other. Depending on the mood of your art piece, contrast can work to your advantage. But first, make sure you understand the principles of how to use contrast in art.
For example, simply using different colors next to each other creates contrast, but when they are the same value too, it can create "vibrating" colors. If you want a really vibrant piece, you can use this technique, but it can also be hard on the eyes. See the upper left square of our example.
Maybe you want your design to be subtle and sophisticated. This is especially intriguing in cut paper designs. When you cut designs out of paper, the contrast is created by the shadows and negative spaces your cut designs create. Placing it on the same color as what you started with, creates a "white on white" effect where you have very low contrast but can add texture to your piece. In our example, the lower left corner shows very low contrast.
If you need to be able to read words or typography in your piece, you want to make sure to have good contrast between the foreground and background. Or if you want to direct attention to a certain part of your design, you can certainly accomplish this with contrast as well. The upper right square of our example shows great contrast between the word and the background it is on. The lower right square shows contrast between the different elements in the design. So when you are planning your next art piece, think about contrast and how it can help set the right mood or act as a tool.