On a simple level, one can regard a typical computer as a mathematical computing and storage device.
It can use data as input, do some calculation and store the processed data again.

Analog <–> Digital <–> Analog

The computer operates on a binary level.
It therefore has to convert any input to a binary format.

Input-devices transform analog data into the digital, binary language a computing device can understand.
Think of scanning pictures or capturing sound-waves.

On the other end, the computer can output stored data as ‘information’.
In order to do so, it makes use of so called ‘production-devices’ to convert the binary data to useful information again.
I would like to call them DA-devices.
Think of a screen, a soundcard connected to your speakers or a printer.
A printer, on a closer look, can print out a book, by transforming the information (a good SF-story) on pieces of paper, ink and electricity.

Such a production-device transforms information stored inside the computer with the use of consumptional goods back into ‘real’ or analog commodities.
Note that this function may be limited or prevented when surveyed by a so called DigitalRestrictionManagement = DRM.

As you may confirm by your own experience, there are many differences between information inside the computer and analog commodities.
For example, you can use the ‘produced’ goods without the computer itself.
The digital data can be used over and over to make many ‘produced’ goods out of one set of digital information.
You can also vary the quality (eg. resolution, black-white, color) for your produced goods, when you have different DA-devices.

This is whats happening everyday with millions of computers and DA-devices all over the world.

Miniaturization

Many times, you transfer information from or to the computer from or to another digital device, like a mobile phone or a camera.
These devices could be seen as mini-computers.
They classify as this although they maybe trimmed down and only good for certain functions. This is done to make them portable.
Whenever a ‘full-grown’ computer is not useable (cable-connection to the powerstation), a minicomputer might do the trick.

With continuing trend of minituriazation and the rise of the minicomputers, its necessary to digitize more and more information and keep it digital through all device-transfers.
In order to be useful, the devices must be compatible for each device that is storing the data at that time.