The design principle of abstraction lets people build on the work of others.
You can walk to someplace. You can abstract the function of travel and use a horse or a boat or a car or truck or bus to get from one place to another.
So we have cars, and everybody knows how they work. There is your steering, your accelerator, there are the brakes. Abstracting that functionality frees us from knowing how it works. People can say, hey let’s make a truck, or a bus or a formula one racer.
You can do maths with numbers written on paper, and you can move information by taking a folder of papers out of a drawer in a cabinet and putting it a different place, another drawer or cabinet, or on your desktop. Display of information on paper takes advantage of ambient light reflected off a surface just like the ambient-light LCD grids on some of the most useful e-readers.
You can do your maths in a modern processor, to decode a movie maybe, or remove the red-eye from the picture of your fiancĂ©e’s party face, the data are now representations of information in number form, the transfers go from place over circuits and cables. Display on most computers these days is some form of LCD grid circuits, backlit with lamps.
Computer function is abstracted into an operating system, like MSWindows or MacOS or Android. That basically gives us the abstracted abilities to move data, transform data, and display data.
On top of that abstracted facility people can build apps, a spreadsheet program or a streaming video player or a photo editor. Or angry birds.
You can abstract the functionality of the spreadsheet program into a macro language and people will build applications on top of that to run in the spreadsheet engine.
You can abstract the basics of human life and implement them in ‘Second Life’ and people will build mansions with their mice.
Specialized hardware, like an HDMI port, abstracts the capability to send a lot of data fast over a limited distance. The operating system can assume that will do what it is supposed to, and abstract that into a data channel that a movie decoder can use to pour its output down the throat of the HDMI and out to your tv/monitor.
On the other end specialized hardware abstracts being able to send large amount of data long distances, through relay nodes, to a specific other device. That networkfuntionality is usually abstracted into the ethernet standard (802.11) so the OS doesn’t have to care if the data might go over wires or Wifi radio or a power line, or a fiberglass cable.