The C.R.A.P principles relate to design and stand for: Contrast, Repetition, Alignment and Proximity. Applying the principles makes the information in a document easier for a peoples brains to process.
Contrast stands for the idea to avoid elements on the page who are similar such as; type, colour, size, thickness, shape etc. Contrast is often the most important visual attraction on a page, elements that are not the same should be very different so that they stand out.
Repetition is the repetition of certain elements in the design/web page in order to create familiarity, understanding and retention. Repetition could be embedded using a certain bullet point, colour, shape, headings or a particular format and relates to everything that the viewer may visually recognise. Repeat styles down the page for a cohesive feel.
Alignment how the text and images are placed on a page, to the left, center or to the right. All of these elements should be visually connected, nothing should be out of place or distinct from all other design elements.
Proximity creates related meaning and makes sure that all the related elements or parts of a page are grouped together and close to each other. Consequently, all elements which are not related to each other should be separated from each to clearly communicate that they are different.