Match the Web Site to the Real World

This heuristic states that the elements and terms used within your Web site should match those used in the real world as closely as possible.

Here are two examples:

Your Web site should use the user's natural language, not jargon or technical terms, unless they're Computer Science graduates - try to use "Cost Per Click" instead of "CPC", for example
In the real world, books have an "Index" to help readers find what they are looking for. You should also include one in your Web site to help your users find what they are looking for