Data and information

A computer treats everything as data: raw, unorganised facts (numbers, words, images, sounds). When data is processed, it becomes meaningful information. The marks of each student are data; the class average and the topper's name are information. Inside the computer, all of it is stored in binary.

Data comes in three types:

• Structured data follows a strict structure, usually a table of rows and columns: attendance registers, sales records, railway bookings, ATM transactions.
• Unstructured data has no pre-defined format: audio, video, graphics, ordinary text documents, social media posts, satellite images.
• Semi-structured data has no fixed table structure, but uses tags or markings to separate its parts: an email (with To, From and Subject), a web page in HTML, a CSV file (values separated by commas).

Working with data involves:

• Data capturing: gathering data in digital form, through keyboards, barcode readers, sensors and so on.
• Data storage: keeping it safely for later use; large organisations use data servers.
• Data retrieval: fetching it when needed. As data grows, fast access matters more and more.

Deleting a file usually only marks its space on the disk as free; the data stays there until something new is written over it. So 'deleted' data can often be recovered, which is useful after a mistake, but a risk if someone else gets your old device.

To protect data, use passwords, limit access to those who need it, encrypt it (scramble it so only the right people can read it), and shred (securely erase) data before throwing away or selling an old device.