An overview, as in This balcony gives us a bird's eye view of the town, or This course gives you a bird's eye view of history—from Eolithic man to the Gulf War in one semester. This expression can be used literally, for a panoramic view such as a bird might see, as well as figuratively. [c. 1600]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.