Microsoft is claiming 235 of its patents are being violated by distributors of free software.
Fortune magazine reported this week that Microsoft is targeting software such as the Linux operating system — used by big companies including Wal-Mart and Goldman Sachs.
Roger Parloff, who wrote the article, says Microsoft wants big users of this free, rival software to pay them.
He thinks Microsoft has both a valid patent complaint and wants to play business hardball.
A rise in patent claims by technology companies like Microsoft is one cause of the growing logjam at the U.S. Patent Office.
John Doll, the U.S. commissioner for patents, explains how the increase in the number of patent applications has strained the system. He also notes that the patent office is trying to hire more examiners.