While almost everyone who uses the net has heard of Friends Reunited, relatively few will be familiar with Bebo, unless they happen to be a teenager.
In the 13 months since it launched, Bebo has racked up more than 22 million members. It is aimed at those aged 13-30 but has proved particularly popular with school and college students.
Bebo is a social networking site that lets members share pictures and messages with friends that are also on the service. As such, it stands alongside sites such as MySpace, Friendster and many others.
"For it to be fun, you have to connect with your friends," Bebo boss Michael Birch told the BBC News website. "So you badger them into signing up.”
Often, he said, someone at one school or college will sign up and soon afterwards loads of other pupils at the same place will join too.
But this popularity has come with a price. Some schools and colleges have stopped pupils from using the site and block access to it during the school day.
One school that has banned Bebo is Kent College, an independent girls school near Tunbridge Wells.
Debbie Cowley, technology teacher at the college, told the BBC she was concerned about what pupils were sharing via the site. Some were posting personal details, pictures and even making disparaging comments about the school and its staff.
Ms Cowley said she was not happy with the level of security on Bebo and wanted more warnings about the potential dangers of sharing too much information.
In response to these concerns, Mr Birch said: "As I understand it, some schools have blocked us and they block many sites as a matter of course if they are not directly related to school work.
"We do include a link to safety tips on our homepage and at the footer of every single page on the site.
"We are continuing to look at new ways of educating users."
Friends Reunited was a huge success with the first generation of people that went online because it allowed them to find old schoolmates and catch up.
By contrast Bebo is aimed at a generation growing up with the net who, thanks to its wide reach and new ways to communicate, will never lose touch with their school friends.
British-born Mr Birch said Bebo was designed to be like Friends Reunited but with features that encouraged people to come back.
By contrast, he said, on Friends Reunited, once you have the contact details for old friends you do not have much reason to go back to the site again.
Mr Birch said it was just about to add in a system which would let people upload photos from their mobile phones to their Bebo pages.
"Everyone is taking pictures with their mobile phone but doing nothing with them," he said. Charging systems on current mobile networks make it difficult for people to share them with lots of their friends.
Every update prompts an e-mail about the change to those interested which can kick off another round of visits.
Mr Birch said his extended family uses Bebo and its blogging and picture storing features to keep up with everything that is going on, even though relatives are spread out across the world.
This is not just occasional contact, he said, adding that it might mark a big change in social relations.
"We're totally in touch with them," he said. "We see their lives evolve through the website."
Because of the involvement it encourages, he believes the site has a long life ahead of it, if for no other reason that if people wanted to leave they would have to persuade all their mates to go with them.
"You invest a lot of time building your network and home page, putting up content and photos," he said, "and there's a certain loyalty to that."
And for those that want to know, the word Bebo does not mean anything specific to founder Mr Birch.
"It's meaningless," he said, "which is good because users can put their own meaning on it."