You've known for ages that Bebo is a social networking site for teenagers and desperate politicians chasing the youth vote. But you've never heard of Facebook or Twitter, and still think meeting new people on the internet is highly suspect. Whatever your age, these factors classify you as an outsider in the social networking revolution. You're what's commonly referred to as a late adopter.

Early adopters quickly acquire a presence on every social network site going, from Bebo to MySpace, Facebook to Second Life.

Late adopters have never heard of half these sites and even when they have, fail to see what the fuss is about.

If you haven't yet become a Beboer or Twitterer, what exactly are you missing out on?

MySpace

This is the old kid on the block. Set up in 2003, it was bought by Rupert Murdoch in 2005 for €430m, which rankles with many users.

Criticised by some as an ugly-looking site with clunky functionality and gaping opportunities for spam, it still manages to grab 230,000 new users every day.

Music is the social glue on MySpace. Bands set up pages to share their music, news and neuroses, a la Lily Allen, who recently blogged about being in "a sea of tears" following remarks made in the media about her weight.

To set up a MySpace page, you have to put some thought in: pick a profile photo, a quote, favourite song, hobbies, films, books and your 'top friends'. You can also decide whether or not to 'pimp' (decorate) your page.

Functions include email, bulletins, blogs, comments, photos, groups, videos and you can make your profile private to keep random punters away.

"On MySpace, you develop a group of friends that you keep in touch with constantly," says PR consultant Jane McDaid.

"At 33, I'm a granny on the social networking scene. When I registered first, the people asking to be my friends were all 22 or 23. Now, finally, my real friends are starting to find me on the site.

"MySpace is like your little black book. It's not beautiful to look at but the layout is practical. Basically, people look at your profile and ask if they can be your friend. The amount of spam you get depends on who you trip upon on your travels but it's not a major problem.

"It's like real life - you meet new people through existing friends. I'm very selective about the MySpace friends I make because I don't want to be inundated with crap - a lot of users make friends just to be seen to have hundreds of them. As an employer, I check out prospective employee's pages, which they're usually very receptive to."

Bebo

Bebo launched in 2005 and broke the one million user barrier in Ireland earlier this year.

Users are typically teens but ages can range from 10 to 24.

Reflecting this, the site is colourful, bright and simple and has a section for parents on safety issues.

Bebo allows you to upload photos, make comments, send emails and blog.

There is also a push into the music side of things with plans to allow users to share music and download tracks.

A popular feature is the whiteboard, where you can draw pictures.

Sarena Bouchier-Hayes (23) has been a Beboer for the last three years.

"Anyone can look at your Bebo profile if it's public and people can find you through other people, unlike sites like Facebook which are more closed-off," she says.

"You get random punters leaving messages but nothing too bad and you can block people if you want.

You can also privatise your page. I do think some Beboers are too young. You see photos of 15-year-old girls wearing half nothing."

"You use social networking sites based on the fact that all your friends are on them. With Bebo, you can see what everyone is up to, share photos from nights out instead of emailing them to everyone and get comments about them. It's another layer of communication with your pals, a way of meeting new people and keeping in touch with established friends.

Second Life

Second Life is perhaps the most creative and innovative of all the social networking sites and appeals immediately to thirtysomethings.

With over six million users and an average age of 33, it is literally a second virtual life where you create an avatar (usually better looking than the real you because you're allowed to customise features), learn to walk or fly, chat with people in bars using your voice or keyboard, buy property, listen to live music, have virtual sex and, crucially, earn money.

Real people are starting to make big money on Second Life, selling fashion, music, property, educational tools and endless other services.

Second Life has its own currency, the Linden Dollar, but companies pay hundreds of real euros each month to have a presence on it.

There's a Second Life Dublin, complete with the Blarney Stone pub, one of the most popular hits on the entire website.

Jane McDaid has two Second Life avatars - Think Kilda, which she uses for work, and Jane Chariot, for personal visits.

Her company, Thinkhouse PR, has had an office on Second Life since November.

"Our Second Life office is really cool because it's situated opposite the Blarney Stone pub and people are always popping in. The number of hits on our company website has trebled since November. If we're having a real-life launch, we hold one on Second Life too. I'm really curious to see how the site develops; we're only tipping the iceberg at the moment.

"Creating your avatar is great fun. You can change its name and look, give it a tan in summer, re-invent yourself as often as you like. Learning to walk and fly takes ages - you find yourself sitting in the bar chatting to someone, facing the wall instead of the person, but you get the hang of it.

"Second Life is remarkable, it's more creative, visually arresting and stimulating than other sites. There's a very strong culture that you have to get a feel for. It's also great for networking. I've chatted to marketers and DJs in New York and I've made some really good media contacts in Ireland through it."

Facebook

Facebook, a similar site to Bebo, looks incredibly plain but has been described as a free, souped-up Friends Re-United, with links to universities and colleges.

Britain's Prince William is said to have signed up recently.

"There's so much more to it," says Matt Matheson, a 23-year-old Canadian living in Ireland.

Matt is an early adopter with My-Space, Bebo, Facebook and Second Life accounts.

"You can share photos on Facebook with people who are in your network, have a running dialogue on your 'wall' and keep tabs on what your friends are doing. You can also 'poke' people, which simply means to wave at them but sounds like something much more interesting. Facebook is very popular in America, whereas Bebo isn't very well known at all. It's also more private, you can limit the number of your profile that people can see.

"I use different sites depending on who I want to talk to, different friends are on different ones. Social networking sites are the easiest way of keeping in touch, I use them more than email and I never, ever get bored with them."

Twitter

Twitter acts as a kind of hub, allowing you to send brief messages to lots of friends telling them exactly what you're doing at that exact moment in time.

It is described as a global community of friends and strangers (twitterers) answering one simple question: 'What are you doing right now'?

Relatively unknown in Ireland, it has failed to impress some critics, who say the technology is simplistic and there's no real point to it.

"If you have a busy social life, it's a way of keeping tabs on friends because it allows you to answer that one simple question from your mobile or computer," says Fergal Breen from irishdev.com.

"It's a bit daft, though. I can't see the long-term appeal. Where we're going to see real developments in the next few years is mobile phone profiling, connecting with mobiles that share a similar profile to yours."

Do's and don'ts of social networking

* Be aware that there can be a subtle underlying dating theme on many sites, even flickr.com which is primarily a photo-sharing site.

* Remember that employers check MySpace and Bebo pages to see what job applicants are like. So no dodgy photos or stories!

* Don't set up a social network site page if you have committed, or are considering committing a crime. Journalists sweep sites for links to interesting stories.

* Choose your profile name carefully because you usually can't change it afterwards.

* If you're declining a request for friendship on MySpace or Bebo, don't send 'do I know you?' messages - just politely ignore the request.

* Keep work and social networking separate. It might be best not to invite workmates onto the site unless you want your outrageous stories to go around the office.

* Don't flirt or discuss private matters on your friends' public walls - this is considered a social networking no-no.

* Remember that your work IT department sees everything.

* If you're a parent allowing your teen to set up a Bebo account, check the safety information section first.

* If you're tired of Facebook and Twitter, check out www.frappr.com; www.last.fm.com; www.habbo.com; www.linkedin.com ; and www.stumbledupon.com