A "stream" is the live flow of digital information. A "lifestream" refers specifically to the live flow of an individual's information by syndicating their comments through multiple online outlets. In other words, a lifestreaming tool enables your messages to automatically ripple out to Facebook, Twitter, LinkedIn, your blog, and video- and photo-sharing Web sites. Post to a lifestreaming tool and be published everywhere.
The term lifestream was coined by Eric Freeman and David Gelernter at Yale University in the mid-1990s to describe "...a time-ordered stream of documents that functions as a diary of your electronic life; every document you create and every document other people send you is stored in your lifestream. The tail of your stream contains documents from the past (starting with your electronic birth certificate). Moving away from the tail and toward the present, your stream contains more recent documents --- papers in progress or new electronic mail; other documents (pictures, correspondence, bills, movies, voice mail, software) are stored in between. Moving beyond the present and into the future, the stream contains documents you will need: reminders, calendar items, to-do lists."
"People ask what the next web will be like, but there won’t be a next web. The
space-based web we currently have will gradually be replaced by a
time-based worldstream. It’s already happening, and it all began with
the lifestream. This lifestream — a heterogeneous, content-searchable,
real-time messaging stream — arrived in the form of blog posts and RSS
feeds, Twitter and other chatstreams, and Facebook walls and timelines.
Its structure represented a shift beyond the “flatland known as the
desktop” (where our interfaces ignored the temporal dimension) towards
streams, which flow and can therefore serve as a concrete representation
More recently lifestream morphed into meaning your online activity stream as opposed to life in the real world.