Facebook has brought about a major change in the way people communicate with each other and for many their friendships now depend on it, according to an Australian study.

Facebook and other online social networking sites are now "ingrained" and for many people their friendships depend on them, local media today reported quoting the study.

The study found that there were just three per cent of respondents aged 18 to 30 not having a Facebook profile or equivalent, it said.

Among respondents aged up to 80 years, the percentage of those who shun all forms on online social networking is still less than 15 per cent.

"It is really ingrained in our society now," Rebecca Mathews, a researcher at the Australian Psychological Society (APS), said. "It is a major change in the way we communicate.

I guess the telephone being invented was another major one that is comparable."

Mathews polled more than 1800 people and found, overall, that 86 per cent were using online social networking - the vast majority using Facebook but also sites like Twitter and RSVP - and for many it was now part of their everyday routine.

Over 53 per cent of respondents said the websites gave them more regular contact with friends and family, while 79 per cent said it fostered closer ties with those living far away.

About a quarter of around 26 per cent said they went out more and had more face-to-face contact as a result online social networking.

Over 50 per cent of users aged 18 to 30 said they would "lose contact with many of their friends if they stopped", which raises the hypothetical question of what if Facebook was ever switched off’ "I don't think we'd fall in a heap, but it would be a major adjustment," Mathews said.

"Once we introduce technology we really struggle to go backwards and, overall, we do think it is a positive."

More than a quarter of 28 per cent reported a "negative experience," such as harassment or unwanted contact, from online social networking but Mathews said this matched rates of bullying in schools and workplaces.

"It may not be be that online social networking sites are a vehicle for negative experiences and bullying but just another forum in which they occur," she said.