Impact is a sans-serif, compressed font with very thick strokes and little white space. Its characteristics make it a high-impact font, as its name suggests. Sans-serif fonts are commonly used on the web because the small tails on each character of a serif font can have a blurring effect when read on a computer screen.
Impact is good for headlines but seldom used for body text due to its compressed letter-spacing. It is easy to read and grabs the attention of the viewer, but becomes unwieldy when overused. It is considered a web-safe font, meaning that it is common to most operating systems and browsers.
In 1965, a time when condensed, bold typefaces were fashionable, Geoffrey Lee designed Impact for the Stephenson Blake foundry. Impact version 2.20 became a Core font for the Web released with Microsoft products in 1996. Microsoft later released updated Impact font versions 2.30, 2.35, 2.36, 2.37 and 5.0.
If you don't own a software product that supplies the Impact font, it can be purchased, downloaded and licensed for different uses from Ascender Fonts by Monotype Imaging, which holds the copyright to Impact.