In Computer networking, the term data is nothing but any entity that conveys meaning or information. The main purpose of computer networking is to enable and facilitate sharing of data between different computers in the world.
For e.g. different forms of plain/encoded text like computer files, electronic mail messages,web page html data, company employee records, student records etc. ; different forms of multimedia content like audio data, songs, still images/pictures/photos, video images, audio and video movie content, news reports having audio, video and text content etc.
There are two basic representation types for native data, namely, analog and digital.
As shown in the diagram,
- Analog data is continuous & can take infinite set of values. In the diagram, the data takes a wide set of voltage values (v) at different points of time (t). Examples of analog data are audio from a speaker, video output from a camera etc.
- Digital data is discrete and not continuous. It cannot take an infinite set of values and it only takes a finite set of values. In the diagram above, the data takes only two voltage values (+v and -v) at different points of time (t). Examples of digital data include Text files (finite set of characters), binary representation ( in 0s and 1s) of any data like that used in computer arithmetic, bitmap file etc, digitally converted audio, video data, digital images, pictures, digital movie etc.
Note: Though raw data type can be either analog or digital, usually computers can understand only digital data. Therefore, even if raw analog data is to be transmitted between two computers, the analog data is first converted into digital form, to convert it into digital data, before it is sent to other computers. E.g. Voice over IP or Skype calls, where the audio that we input to the computer is in analog form, but it is first converted into digital audio samples through an internal device called codec and then transmitted out of our computer.