1969: On Sept. 2, two computers at University of California, Los Angeles, exchange meaningless data in first test of Arpanet, an experimental military network. The first connection between two sites - UCLA and the Stanford Research Institute in Menlo Park, Calif. - takes place on Oct. 29, though the network crashes after the first two letters of the word "logon." UC Santa Barbara and University of Utah later join.
1970: Arpanet gets first East Coast node, at Bolt, Beranek and Newman in Cambridge, Mass.
1972: Ray Tomlinson brings e-mail to the network, choosing "at" symbol as way to specify e-mail addresses belonging to other systems.
1973: Arpanet gets first international nodes, in England and Norway.
1974: Vint Cerf and Bob Kahn develop communications technique called TCP, allowing multiple networks to understand one another, creating a true Internet. Concept later splits into TCP/IP before formal adoption on Jan. 1, 1983.
1983: Domain name system is proposed. Creation of suffixes such as ".com," ''.gov" and ".edu" comes a year later.
1988: One of the first Internet worms, Morris, cripples thousands of computers.
1989: Quantum Computer Services, now AOL, introduces America Online service for Macintosh and Apple II computers, beginning an expansion that would connect nearly 27 million Americans online by 2002.
1990: Tim Berners-Lee creates the World Wide Web while developing ways to control computers remotely at CERN, the European Organization for Nuclear Research.
1993: Marc Andreessen and colleagues at University of Illinois create Mosaic, the first Web browser to combine graphics and text on a single page, opening the Web to the world with software that is easy to use.
1994: Andreessen and others on the Mosaic team form a company to develop the first commercial Web browser, Netscape, piquing the interest of Microsoft Corp. and other developers who would tap the Web's commerce potential. Two immigration lawyers introduce the world to spam, advertising their green card lottery services.
1995: Amazon.com Inc. opens its virtual doors.
1996: Passage of U.S. law curbing pornography online. Although key provisions are later struck down as unconstitutional, one that remains protects online services from liability for their users' conduct, allowing information - and misinformation - to thrive.
1998: Google Inc. forms out of a project that began in Stanford dorm rooms. U.S. government delegates oversight of domain name policies to Internet Corporation for Assigned Names and Numbers, or ICANN. Justice Department and 20 states sue Microsoft, accusing the maker of the ubiquitous Windows operating system of abusing its market power to thwart competition from Netscape and others.
1999: Napster popularizes music file-sharing and spawns successors that have permanently changed the recording industry. World Internet population surpasses 250 million.
2000: The dot-com boom of the 1990s becomes a bust as technology companies slide. Amazon.com, eBay and other sites are crippled in one of the first widespread uses of the denial-of-service attack, which floods a site with so much bogus traffic that legitimate users cannot visit.
2002: World Internet population surpasses 500 million.
2004: Mark Zuckerberg starts Facebook as a sophomore at Harvard University.
2005: Launch of YouTube video-sharing site.
2006: World Internet population surpasses 1 billion.
2007: Apple Inc. releases iPhone, introducing millions more to wireless Internet access.
2008: World Internet population surpasses 1.5 billion. China's Internet population reaches 250 million, surpassing the United States as the world's largest. Netscape's developers pull the plug on the pioneer browser, though an offshoot, Firefox, remains strong. Major airlines intensify deployment of Internet service on flights.
2009: The Seattle Post-Intelligencer becomes the first major daily newspaper to move entirely online. Google announces development of a free computer operating system designed for a user experience that primarily takes place on the Web.