What data is

Data is a collection of characters, numbers and other symbols that represent values of some situation or thing. (The singular is datum.) On its own, data means little; once processed, it helps us make decisions: choosing a college from its past results, planning schools and hospitals from census data, an airline's dynamic pricing of tickets by demand, or weather alerts from satellite readings.

Data comes in two broad kinds:

• Structured data has a well-defined format, usually a table. Each column is an attribute (a property, such as Name or Marks), and each row is an observation (one record, such as one student). A fee slip, with the same fixed fields every time (name, class, roll number, amount, date), is structured data.
• Unstructured data has no fixed row-and-column structure: newspaper pages, emails, web pages, audio and video, and social media posts.

Metadata is data about data. An email's metadata includes its subject, sender, recipient and date. An image file's metadata includes its size, type and resolution. Metadata helps us organise and search data.