1. Any information or data that is sent to a computer for processing is considered input. Input or user input is most often sent to the computer using an input device such as a keyboard or mouse. The picture is an example of input being sent from the computer keyboard to the computer.
2. In general, input can also refer to a contribution of feedback, information, or work. For example, someone may ask you for your input about a project they have undertaken at work or school.