Data and why we need it

Data are numbers that represent measurements from the real world. A single measurement is a datum.

Information is a meaningful answer to a question, obtained by processing data. Data become information only when they are organised and studied.

Geography uses a lot of data, because relationships between places are best explained in numbers. To study the cropping pattern of a region, or the growth of a city, we need many kinds of data: area, production, population, land use, and so on.

But data must be presented carefully. The book tells of a man who was told that a river's average depth was less than a metre, so he tried to walk across, and drowned: the average hid a point where the river was much deeper. An average alone can mislead; we need to know how the values are spread too.

In short: data become information when they are processed and presented properly.