Dimensions can be thought of as perspectives on a subject. Let’s say your subject of interest is sales. One way of analyzing sales is by time. How many widgets did we sell last month? Last quarter? Last year? This is a time dimension. Maybe you want to look at your sales data by geography. What were our sales in Beijing? China? How about all of Asia? This is a geography dimension. Product or product category might be useful. What was my best-selling product? Are there any product categories that aren’t hitting their sales targets? This is a product dimension. Having multiple perspectives or dimensions with which to view the subject is very powerful. This allows you to put them together and get answers to even more detailed questions. What was the worst selling product category in Beijing last quarter?