What is the way of communication between external world and computer?

Which of the folloiwng technology for data storage is related to light ?

What is the output device used by traffic signal lights?

Which printer prints one character at a time?

What is the general name of key board used in computers?

What is the collection of facts that are unrecognized but able to be organized into useful information?

What is the office automation package of Microsoft?

What is the medium used by the input device light pen for graphical input ?