Now, in order to call up older posts in profiles, Facebook users have to click a button that expands the activity stream list, a poor user experience, Zuckerberg said.

Instead, Timeline is "the story of your life," he said. It will be available in a few weeks.

If the most recent version of the profile provides fodder for a 15-minute chat, Timeline offers enough information for an in-depth, hours-long conversation about a person's life, he said.

People will also be able to fill in the Timeline retroactively with old photos and place them in the appropriate chronological spot. Current privacy settings and controls will apply to the Timeline interface so people can establish who can see what.

Timeline will also feature a new Ticker section, where Facebook will put automatically generated notifications of user actions, such as when people "like" a webpage or establish new friend connections.