Facebook, once a small, "free" social networking site for university undergraduates to share personal information, has become a vast subdivision on the information super highway.
It is expected soon to reach a landmark figure of 500 million registered users.
Its value is put at about $20 billion and it is at the vanguard of the social networking revolution, having outlasted several other variations on the theme, notably MySpace and Bebo.
It has taken the concept further than was dreamed possible a mere six years ago when it was established by 20-year-old university student Mark Zuckerberg - to the extent that users today often appear to inhabit a different and somewhat parallel universe to their non-wired counterparts.
But some facts transcend universes, and it is only now beginning to dawn on Facebook habitues that a truly free networking site might be closer to wishful thinking than reality: even in the utopian realms of the Internet there is, it seems, no such thing as a free lunch.
This much has become loudly apparent of late with the airing of concerns about Facebook's privacy settings.
On Monday this week - "Quit Facebook Day" - Canadian campaigners urged people worldwide to remove themselves from the site.
They, and many others, were riled about the way in which they felt their privacy was being purloined for profit.
Quite why they should have been so surprised is another matter: you do not pay upfront to belong to Facebook, but the company must make ends meet - and a tidy profit - somehow.
That "somehow" is no great secret.
The site sells advertising to companies tailored to the defined demographics of its users.
The "footprint" they create in their Facebook activities is like gold to advertisers and marketers who will pay accordingly.
Just as it is naive for users who are careless with their basic settings - for instance, as to who can access or "participate" on their page - it is equally artless to be disconcerted that information about them is harvested, packaged and used for commercial ends.
There is substance, however, to the complaint that, at least until last week when Mr Zuckerberg called a press conference to announce new policies, the privacy settings on the site were so complex and convoluted they required more than average persistence and determination to understand and amend.
There were, for instance, 150 choices or boxes to tick or un-tick.
Many users have begun to see this as unnecessarily, perhaps even deliberately, obtuse.
Others, having exhausted the novelty value of networking, have belatedly discovered there is such a commodity as privacy and they would like to hold on to it.
Still more seem resentful that the Zuckerbergs of this world - so-called cool, hip dudes - should become determinedly wealthy on the back of aimless, friendly and hitherto harmless networking.
Concern over privacy issues on social networking sites is not new. Early on, parents began to see the risks inherent in their children posting information and pictures on sites such as Bebo.
Cyber-stalking and sexual grooming by paedophiles remain a concern, on Facebook and elsewhere.
Data harvesting raises the prospect of information posted on such sites potentially being used by credit agencies, healthcare providers or even employers.
Have no doubt that "private" information shared on such sites can find its way into the public domain - often to the pain of family and friends.
Nor, once the gathering of information becomes an urgent financial prerogative, have the various cyber operations proved to be any more scrupulous than traditional companies: witness the furore over Google Maps having mined local residents' personal details while engaged in its mapping exercises.
Regardless of whether the protestations grow, or whether Facebook's new policies will salve concerns, at the very least such networks are forcing consumers to reassess what privacy means in a universe in which personal details are swapped with libidinous abandon.
Those waking up to the fact they may have given away more than they had intended are now seeking something of a morning-after pill: the ability to control what information about them is floating about in cyberspace.
For active members of the Facebook community who have to date remained oblivious to the implications, it may be too late; for those yet to join, but who arrive with a greater awareness of such issues, Mr Zuckerberg's claim of 2009 that "the age of privacy is over" is beginning to seem not only premature, but also to have been touched by an unseemly hubris.
