Data type define the nature of the data. We can distinguish the original data, which can be text, charts, images, sound or objects, and the digital representation of these types of data that determines how the software has to handle them. The two most important data types are ‘string’ and ‘numerical’. Numerical data consist of only numbers. String data consists of characters (this may include numbers, but numbers are not interpreted as such, so it is not possible to make calculations with string data).