Data is now being used in a very wide sense. But actually data is information in its very raw form. It is facts and figures that need to be organized in order to make some sense out of them. Data would be useless if it is not assembled together properly. The act of 'taking in' the information or data is called input.
Input means getting the data from the user which is essential in order to produce a result.
The data itself is not the input, it is the act of feeding that data into the computer. For example to make a pay-sheet, you are required to enter different pieces of information such as the worker's name, the numbers of hours he worked etc. Output on the other hand, is everything that you derive out of the a computer program. The result of the input is called output. When data has been fed into the computer, it will be worked on and a result would be generated, this result is referred to as output.