Intermediate 
On one day in August, one in seven people on Earth, 1 billion people, used Facebook, according to founder Mark Zuckerberg. In ten years, the social network has completely changed peoples relationships, privacy, their businesses, news media, helped to end regimes and even changed the meanings of common words.
A more open and connected world is a better world. It brings stronger relationships with those you love, a stronger economy with more opportunities and a stronger society, wrote Zuckerberg.
These are just some of the ways his company changed everything  for better or worse.
1 Facebook has changed the de nition of friend To friend is now a verb. And, unlike in real life, it is easy to unfriend someone, a word invented to describe ending a Facebook friendship when that person is no longer improving your Facebook newsfeed.
Although the meanings of the words share and like are basically the same, Facebook has made the terms more important to us.
School and university reunions are unnecessary  you already know whose career is going well, whether the perfect pair have split and youve seen pictures of your schoolmates babies. You wont be surprised to see an ex in the street with a new girlfriend or boyfriend: you already know theyre dating someone else from the romantic sel es.
But, unlike in real life, on Facebook, all your friends have the same importance. A classmate from university who you havent seen for 15 years, a friend-of-a-friend from a party or a colleague youve never actually spoken to in person  they are all Facebook friends in the same way as your closest friend or your spouse or your mum.
It doesnt necessarily mean we see them the same way. Professor Robin Dunbar is famous for his research that suggests a person can only have about 150 people as a social group. Facebook hasnt changed that yet, he believes. But Dunbar says he fears it is so easy simply to end friendships on Facebook that, eventually, people may not need to learn to get on with each other.
2 We care less about privacy The surprising thing is that Facebook users happily hand over their information.
Pew Research Center found that most young people are more than willing to hand over their details. Ninety- one per cent post a photo of themselves, 71% post the city or town where they live, more than half give email addresses and a  fth give their phone number.
But, because so much of a persons life is shared online, Facebook gives people a way to create an image and a fanbase. Academics have described a new phenomenon: the Facebook self.
More than 80% of Facebook users list their interests, which allows brands to target them effectively. But most younger users limit who can see their pro les, with 60% allowing friends only.
3 Facebook has created millions of jobs  but not in its own of ces Facebook provides indirect employment for people whose job it is to make Facebook work for their brand.
It is a tool like no other, said Michael Tinmouth, a social media strategist who has worked with brands such as Vodafone and Microsoft. Marketers have an understanding of a brands customers like they have never had before. The data available is extraordinary. You know who your customers are, who they are friends with and how they engage with your brand.
And advertisers pay a lot for that. Facebook reported advertising revenue had increased by 46%, reaching $3.32bn.
Facebook is also a mine eld for brands. Suddenly, customers dont simply complain on the phone to a customer service representative or on a small specialist internet forum  angry customers can post their complaints for hundreds of their friends to see or even on the brands own page.
4 Facebook has been the tool to organize revolutions Organizing demonstrations and direct action has been revolutionized by Facebook. Manchester Universitys Olga Onuch found Facebook had been the key way for reaching half of all the Euromaidan protesters in Ukraine.
 Many of the people interviewed in Onuchs research said they relied on Facebook for the truth about what was happening  they dont trust traditional media.
5 Facebook makes news, breaks news and decides what is news About 71% of 18- to 24-year-olds say the internet is their main news source and 63% of users overall, according to the Pew Research Center. About a third of Facebook users post about politics and government.
Most people will  rst read an item of breaking news via Facebook or other social media, mostly on mobiles.
Facebook has also changed the ways journalists write stories. It is a resource many reporters cannot now live without. For better or (often) worse, it is a place to  nd information on almost any ordinary person, who might suddenly  nd themselves at the centre of the days biggest news story.
6 Users are changing Facebook It used to be a site for students of top US universities.
In 2014, ten years after its launch, 56% of internet users aged 65 and older have a Facebook account. And 39% are connected to people they have never met in person.
More than ever, the site is a gateway not just to your friends but to the rest of the internet.
We may as well get used to it, said David Kirkpatrick, author of The Facebook Effect. It might very well go away further down the road but something this big takes a long time to disappear, he told BBC Radio 4s Today programme. Facebook has proven its ability to change and it will continue to be a very, very major player.