Also: Big Visible Charts
In agile software development the preferred way of displaying data visualizations is to post them on the wall in the team’s shared workspace (i.e., rather than logging them in a spreadsheet). Examples of information radiators include a burndown chart, a burnup chart, and a task board, although other types of charts are possible. These may also be referred to as Big Visible Charts.
An information radiator displays information in a place where passersby can see it. With information radiators, the passersby don’t need to ask questions; the information simply hits them as they pass.
Keeping information visible at all times promotes transparency (one of the three pillars of scrum).
Background Of The Term
Alistair Cockburn coined the term “information radiator” in 2000 and introduced it in his 2001 book, Agile Software Development.
Information Radiators – Agile Alliance glossary
What makes a good information radiator – ThoughtWorks Australia, Lachlan Heasman – slide deck
Chapter 3: Communicating, Cooperating Teams – extract from Agile Software Development: The Cooperative Game (2nd Edition) by Alistair Cockburn
 From Agile Software Development (2nd Edition) by Alistair Cockburn, Chapter 3.