Environmental scanning is an approach to detecting hidden clues about the future in available information sources. It can be described  as
- the activity of rapidly surveying news media, digesting the literature of science, the literature of popular culture, the literature of just about everything.
"Environmental Scanning is usually conducted at the beginning of a foresight study and is considered to be a pre-requisite to any foresight studies. Environmental scanning involves analysing major trends, issues, innovations, events and ideas in the general environment. The purpose of environmental scanning is to gather information that will aid decision makers in situations where uncertainty is high." 
Generalists are best suited for scanning. A specialist with an interest in nanotechnologies is less interested in processing huge amounts of information related to stem cells, AI and galactic exploration. He is also much less qualified to string together these seemingly unrelated pieces of information and notice key developments in areas outside his expertise.
- What's new, what's happening that doesn't make sense, what links can be made between disparate activities? In scanning, the reader may spot emerging issues. Somewhere where people gather, something new is happening. If it fast becomes mainstream, it will have a dramatic effect on society. The reader scans for the disturbing, the provocative, and the ridiculous, for events that challenge present assumptions.
To a person versed in scanning "everything fits". After a while news about technological developments stop being mere curiosities and become manifestations of future achievements. A news about better walking methods for robots is of little interested to most people, as it is unrelated to any present developments. To someone with a good understanding of the future, however, it is an important milestone on the way to humanoid robots.
- Tag Standard -- a proposed link tagging standard for use by Futures wiki scanners