By Zoe Kleinman
Technology Reporter, BBC News
Cheers... but is this photo an invasion of privacy?
People who post intimate details about their lives on the internet undermine everybody else's right to privacy, claims an academic.
Dr Kieron O'Hara has called for people to be more aware of the impact on society of what they publish online.
"If you look at privacy in law, one important concept is a reasonable expectation of privacy," he said.
"As more private lives are exported online, reasonable expectations are diminishing."
The rise of social networking has blurred the boundaries of what can be considered private, he believes - making it less of a defence by law.
We live in an era that he terms "intimacy 2.0" - where people routinely share extremely personal information online.
"When our reasonable expectations diminish, as they have, by necessity our legal protection diminishes."
Dr O'Hara, a senior research fellow in Electronics and Computer Science at the University of Southampton, gave the example of an embarrassing photo taken at a party.
A decade ago, he said, there would have been an assumption that it might be circulated among friends.
But now the assumption is that it may well end up on the internet and be viewed by strangers.
Privacy has long been a thorny issue but there were very few court cases until that of former motorsport boss Max Mosley in 2008.
Mr Mosley sued the News of the World over the publication in the newspaper of explicit photos of him secretly taken during an orgy.
He argued that the publication of the photos was an unwarranted breach of his privacy - and won.
Mr Mosley had taken steps to keep his private life private but Dr O'Hara's concern is that other people's disregard for privacy online will spill over into other walks of life.
As debates continue to rage over whether the new airport body scanners and CCTV are an infringement of privacy or useful protection, some argue that it already has.
"Recent security decisions have become a privacy discussion - but if security suffers, the community suffers," Dr O'Hara said.
He was due to deliver his research paper at the annual Media Communication and Cultural Studies Association (Meccsa) conference held at the London School of Economics from 6-8 January.