He was born in Poland and grew up in Philadelphia, Penn., his daughter-in-law, Jane Baran, said.
He earned a bachelor's degree in electrical engineering from Drexel University and a master's degree from UCLA.
While working at RAND Corporation in Santa Monica, Calif., he developed the idea of packaging data into discrete bundles, which are then sent on various paths around a network and reassembled at their destination, according to a New York Times article.
The U.S. Department of Defense eventually built its Arpanet network, which was eventually replaced by the modern Internet, based on the ideas of Baran and others.
"I'm tremendously proud of him. It was an entire change of thinking," his son David Baran said of his father's groundbreaking work.
He also founded a nonprofit and seven companies. He and his family moved to the Palo Alto area in 1970, David Baran said.
His wife, Evelyn, predeceased him in 2007. He is survived by his son and daughter-in-law, David and Jane Baran of Atherton; three grandchildren; and his companion, Ruth Rothman.