SAN FRANCISCO — The U.S. government is relinquishing its control of the Internet’s address system in a shift that may raise questions about the future direction of online innovation and communications.

The decision announced Friday begins a long-planned transition affecting the stewardship of the Internet Corporation for Assigned Names and Numbers, or ICANN. That’s a not-for-profit agency launched in 1998 by the Commerce Department to govern the system that assigns website addresses and directs Internet traffic.