This Sunday, October 7, marked the 60th anniversary of the issuing of patent #2,612,994 for the barcode by the U.S. Patent Office to Norman Joseph Woodland and Bernard Silver. The two friends reportedly sought a way to improve the grocery store checkout process. Their design was inspired by Morse code, simply extending the dots and dashes into lines, and the technology of movie soundtracks. Woodland and Silver's innovation has had a lasting impact in commerce and, perhaps more surprisingly, libraries.
The Gallagher Law Library has a thorough guide on conducting patent research. If you're looking to find the text of a particular patent (say, #2,612,994) in a free and quick manner, you can always use Google's Patent Search or the U.S. Patent and Trademark Office's Patent Full-Text Databases.