CARP stands for Contrast, Alignment, Repetition and Proximity. Using these four principles will help you design content that stands out and is effective.
Things that look different are different.
In the “Good Contrast” example above, it’s easy to see the contrast. “Good” is orange and in a-serif font (a font with no little feet on the letters), and “Contrast” is grey and in a sans serif font. Both words look distinctly different.
In the “Bad Contrast” example above, the contrast is harder to see. The only difference between “Bad” and “Contrast” is that “Bad” is in black and “Contrast” is in grey. Since the colors are so similar, neither word stands out from the other.
Contrast can be created in many different ways, but it’s important that the contrast is distinct and obvious.
Things should line up.
In the “Good Alignment” example, the text creates the illusion of a hard left line even though there isn’t an actual line, and the indented text is clearly part of its own category.
In the “Bad Alignment” example, everything looks like it was haphazardly thrown onto the page.
Things that are alike should look alike.
In the “Good Repetition” example, both of the major headings look the same, both of the minor headings look the same, and the body text is the same throughout.
In the “Bad Repetition” example, each heading looks completely different and the body text switches between a serif and a sans-serif font.
Items that are near each other go together.
In the “Good Proximity” example, the heading is close to the body text it goes with, and the image is near the section that refers to it.
In the “Bad Proximity” example, the image is far from the text that refers to it, and the heading is closer to the text of the previous section than the section it goes with.
Remember, if you don’t use CARP, your design will be crap.