Describes an offense that uses multiple wide receivers (usually 3 or more) with the goal to stretch the defense out along the line of scrimmage. The spread wide receivers also run routes to different areas of the field to stretch the defenders vertically and horizontally down the field.
A common misconception of the spread offense is that it's a pure passing attack. While there are variants of the spread that primarily use passing (such as the Air Raid 80% passes), it can also be run oriented. The defensive linebackers are typically spread out more covering wide receivers which opens holes for the runningback or quarterback run option.
The main factor of success running this offense is creating a mismatch with the defenders, such as a linebacker covering a wide receiver. Running a proficient spread offense also requires the quarterback to call/change plays from the line of scrimmage and accurately read defensive coverage.