DO you feel like you're missing out if you do not Tweet? Are you baffled by the mystery of poking people over the internet?

Have you been longing to learn what it all means and why social-networking websites like Twitter, Facebook, Bebo and MySpace are so popular?

People are spending millions of hours a day online, sending messages to mates and looking at photographs of friends on sites like these. But what do they get out of it?

In the simplest form, the sites allow people to send messages to each other but much more quickly than through the Royal Mail.

They can also swap pictures and movies, talk to strangers with similar hobbies and promote their business, bands or interests online.

Christopher Barnatt, associate professor of computing and organisations at Nottingham University's Business School, explained why they had become so popular.

"The use of social networking sites has skyrocketed over the past couple of years for a number of reasons," he said.

"For a start, reliable, low-cost and high-speed internet connections have become available, with about 90 per cent of UK users now having broadband at home.

"This has made it possible for people to exchange photos and video online, which in turn has improved the quality of the communication possible in social-networking sites.

"Text-based online forums have existed since the early 1990s. However, it has been the addition of photos and video that have really made online social networking come to life."

Mr Barnatt cited the increase in mobile phones – which take photos and can access the internet – as a significant factor in encouraging "anytime, anywhere access" to social-networking sites.

"I think the impact has been that many people now live as much in their virtual communities as in their physical communities," he said.

"Indeed, many young people report themselves to be more comfortable communicating online than in real life.

"Social networking sites are more widely used for social communication than e-mail."

The professor said firms had started to wake up to the power of social-networking sites to advertise their business.

And another area booming from the websites is the celebrity culture.

"Sites like Facebook and Bebo have fuelled the culture of celebrity, with everyday happenings becoming instant news within people's online social networks," he said.

"As a result, we are witness to the first generation who are leaving their own multimedia digital footprint as they grow up."

However, the professor said that could become increasingly problematic.

"Already employers routinely checkout job applicants on Facebook," he said. "As the social-networking site generation gets older it is increasingly likely that something in their online past will come to haunt them in the future.

"At present, journalists have to hunt for dirt on politicians or famous people.

"But increasingly, all this embarrassing content will all be available to them in the archives of social-networking sites."

FACEBOOK

Last year Facebook was, and still is, the most popular social-networking internet site in the world, the fifth most popular website overall.

Created in 2004, people can set up an online profile with information like their name, date of birth, who they are dating and what their favourite food and hobby is.

Members can make friends with other people who have signed up to the site – often their friends in real life – or chat via their computer screen to strangers. It is mainly used as way of free communication between friends, compared to costly phone calls or more time-consuming e-mails.

Charlotte Phillips, of Hedingham Way, Mickleover, uses Facebook to keep in touch with relatives.

The 18-year-old nurse, who went to Saint Benedict's Catholic School and Performing Arts College, said: "I can keep in touch with people I haven't seen since I left school.

"I also speak with long-distance relatives, it's better than expensive telephone calls."

Many people – Derby barman Daniel Millward included – openly admit to using Facebook to being nosey about what other people are doing.

"It's a cheap way of keeping in contact with friends and family that live far away," said the 19-year-old, of Dunedin Close.

"But I do enjoy being nosey and reading about what other people are up to."

MYSPACE

Last year Facebook replaced MySpace as the most popular social networking site, although MySpace is still going strong.

It is mainly favoured in the UK by unsigned bands and singers who want to promote their music.

MySpace users, like those on Facebook, can type up a profile of themselves, which includes their favourite TV programmes, musicians and films.

Bass player Drew Davis, 20, of Eggersford Road, Stenson Fields, uses MySpace to promote his group, Rugosa Nevada.

The band formed 12 months ago and regularly plays gigs around the city, including at The Flowerpot, The Vic Inn and the Darwin Suite, at the Assembly Rooms.

MySpace allows him to upload alternative rock tracks and advertise their shows. People can also leave messages and find out about the group's history.

He said: "MySpace is all about the music – it's great for getting unsigned bands noticed. It's like having a replacement for a phone."

TWITTER

One of the most popular features of Facebook is the status update, which allows users to let the world know what they are doing. All of the time.

For example – Bob is...doing the garden; Jess is...making music; Paul is...updating his profile.

It has spawned a new site of its own, called Twitter, where people simply tell the world exactly what they are doing through 'tweets', or text-based posts.

The only rule about a tweet is that it must be made up of 140 text characters or less.

Celebrities like TV presenter Stephen Fry, radio DJ Chris Moyles, magician Paul Daniels and American president Barack Obama are common Twitters.

Even the Evening Telegraph has its own Twitter site, with updates of breaking stories.

BEBO

For youngsters, there's Bebo – an acronym for Blog early, blog often – which is owned by AOL and is aimed at a younger market, but essentially is another site where people can make virtual friends and talk to each other.

Aaron Foulk, 10, of Rothwell Road, Mickleover, goes on Bebo twice a week.

The Silverhill Primary School student said: "I use Bebo to chat to friends I don't see very often. I like making new friends with people and sharing my hobbies with others."

Aaron's mum, Wendy, 39, said she did not mind him using the site, as long as he was educated about the risks young people face on the web.

She said: "I think it's acceptable as long as they are aware of the dangers of the internet and are also staying active, not spending too much time on the computer."

OTHERS

And it's not just the young who have embraced the new technology.

Pensioner Peter Oakley uses BlogTV.com to keep in contact with people across the globe.

The 81-year-old, of Bakewell, featured in the Evening Telegraph last year after his spoof cookery video received more than 50,000 hits on the YouTube website in six days.

He said: "I don't think age should ever be a barrier.''