L'universo digitale può gestire esclusivamente numeri, quindi è necessario descrivere la realtà fisica e le sue informazioni usando soltanto quelli.
In the analog world, what we can consider the real, physical world, information IS the media/objects that contain it (the negative of the shot, the printed photograph, the grooved vinyl records, the moving mechanism of the clock) and vice versa.
In the digital world, information has been described in a series of numbers so it is INDEPENDENT of the medium (the image file, the music file, the time data).
A digital information (file) can be duplicated infinite times and moved to infinite different media while always remaining identical to itself.
Inside a computer, information can be managed by making electronic elements similar to switches.
An information is basically the answer to a question, and the absolute simplest answer that can be given is actually binary: Yes - No
A binary system involves an element that can assume two states: 0/1 - on/off - up/down - empty/full, etc.
The bit (Binary digIT) represents one of these minimal pieces of information materialized differently depending on the hardware used (Hard Disk, RAM, USB stick, CD, DVD, etc...) and yet it remains identical to itself because, in fact, it is simply a number.
Combining bits
Obviously with just one bit you cannot describe much. But using the possible combinations of a group of bits increases the possible answers exponentially:
with 1 bit (2-state) there are only 2 combinations;
with 2 bit (2-state) there are 4 combinations;
with 3 bit (2-state) there are 8 combinations;
with 4 bit (2-state) there are 16 combinations;
…
with 7 bit (2-state) there are 128 combinations;
with 8 bit (2-state) there are 256 combinations;
To know the number of combinations, just raise 2 (the n umber of states; the so-called base) to the number of bits: take 2 and multiply it by 2 as many times as many bits as I want to devote to that packet of information.
Multiples of the bit
1 BYTE (UPPER CASE) is 8 bits (lowercase)
For multiples, the normal prefixes of the metric system are used: kilo > Mega > Giga > Tera > Peta …
Each multiple corresponds approximately (counts should be done in bits, not BYTE) to 1000 times the previous one.
The example of letters: the ASCII code
The A.S.C.I.I. (American Standard Code for Information Interchange) code is a table that assigns meaning (function codes, symbols, numbers and letters) for each combination of a 7-bit system (thus 128 possible combinations) and 1 control bit.
The need becomes to be able to describe the world only with binary numbers.
Sampling or modeling
To describe the analog world with numbers, one can either: sample it (measure it with some precision at regular intervals) or model it (apply mathematical models that best represent it).
It is not possible to completely describe every aspect of reality. Each approach is better at describing some features and less, or even useless, at describing others.
The sampling approach is typically better suited to recording chaotic details but produces very “heavy” files.
The approach through models is typically better suited to recognize “logical” forms but eliminates many details.
Raster graphics or vector graphics
In raster (or bitmap) graphics, pixels are the elements used to sample the image while in vector graphics, curves (vectors) are used to fit and trace shapes
