Interaction

Computers by their very nature are interactive:

• Input
• Process
• Output

Without input computers provide very little function.

However there are different types of interaction.

Initially computers had very physical types of interaction based around switches, on or off.

Later input devices provided proportional or progressive input like game paddles and the mouse.

These forms of input are still not 'natural' for humans.

In user interface design there is a concept of 'direct interaction'. For example instead of choosing a menu item to close a window, you simply click directly on the close button. Instead of typing a command to move a file from location to another, you click and drag the file to its new location. It could be argued that any form of mouse usage is not as direct as it can be. A touch screen is more direct as the finger is in the same vicinity as the item being interacted with. It is more intuitive and requires less training.

There are various forms of touch screens and they have their advantages and disadvantages. The most common currently is the capacitive glass touch screen which supports multiple touch and doesn't require the screen to pressed (just touched).

The iPhone popularised the use of capacitive touch screens and also multi-touch. Apple's early work on the iPhone introduced new forms of interaction such as pinch-to-zoom and swiping. These forms of interaction are also now available on multi-touch trackpads.