Types of Data

Data comes from many different sources, so it arrives in many different formats. An image is a collection of pixels; a video is made up of frames; a fee slip contains a few numeric and non-numeric entries; messages and chats mix text, icons (emoticons) and images or videos. To handle this variety, data are classified — on the basis of their format — into two broad categories: structured data and unstructured data.

(A) Structured data

Data which is organised and can be recorded in a well-defined format is called structured data. It is usually stored in a computer in a tabular form — rows and columns — where:

• each column holds the data for one parameter, called an attribute (also called a characteristic or variable), and
• each row holds the data of one observation across all those attributes.

A shop's inventory of kitchen items is a classic example:

Because the format is fixed, software can compute with it directly. Using a spreadsheet or similar software, the shop owner can find the total number of items simply by summing the Items_in_Inventory column. The owner can also work out the total value of the whole inventory by multiplying each entry of the Unit Price column with the corresponding entry of the Items_in_Inventory column and adding up the products.

Different activities maintain different sets of attributes, but the tabular idea is the same everywhere:

(B) Unstructured data

Now think of a newspaper. Its news items are also data, but there is no fixed pattern governing how they are placed. One day a page may carry three images of different sizes, five news items and one or more advertisements; another day it may have one big image with three textual news items. There is no particular format, no fixed structure for printing news.

An email is another example. Nothing fixes how many lines or paragraphs you must write, or how many files you may attach.

In short: data which are not in the traditional row-and-column structure are called unstructured data. Examples include web pages consisting of text along with multimedia content (images, graphics, audio/video), text documents, business reports, books, audio/video files, and social media messages. …