Tucked into yesterday's Facebook IPO filing was a letter from its (now very rich) CEO Mark Zuckerberg, who laid out his "social mission" to connect the world and make it more open.

"Facebook aspires to build the services that give people the power to share and help them once again transform many of our core institutions and industries," Zuckerberg wrote.

Back in the Harvard dorm room where Facebook took shape, however, "Facebook was not originally created to be a company." Instead, Zuckerberg envisioned a platform that would enable connections.

"At Facebook, we're inspired by technologies that have revolutionized how people spread and consume information," Zuckerberg wrote, pointing to the printing press and the TV. Today, we have the Internet and mobile phones.

"Facebook aspires to build the services that give people the power to share and help them once again transform many of our core institutions and industries," he said.

While privacy advocates might beg to differ, Zuckerberg said "there is a huge need and a huge opportunity to get everyone in the world connected, to give everyone a voice and to help transform society for the future."

The scale of this push is "unprecedented," which is where Facebook will focus its efforts. Ultimately, the company wants to strengthen how people relate to each other and improve how people connect to businesses and the economy.

"People sharing more — even if just with their close friends or families — creates a more open culture and leads to a better understanding of the lives and perspectives of others," Zuckerberg said. "As people share more, they have access to more opinions from the people they trust about the products and services they use. This makes it easier to discover the best products and improve the quality and efficiency of their lives."

That sentiment is behind Facebook's "open graph" concept. Last year, Facebook teamed up with a variety of companies to launch apps that let users share their activity from across the Web on Facebook. Did you listen to a song on Spotify, read a news story on washingtonpost.com, or watch a TV show on Hulu? All that activity can automatically show up on your newsfeed with the click of a button.

There was concern that people might not want to share all their non-Facebook Web activity with the social network. But during a November appearance on Charlie Rose, Zuckerberg said your friends will likely provide the most useful recommendations. "Do you want to go to the movies by yourself or with your friends?" Zuckerberg asked.

That assumes, of course, that your Facebook "friends" are actually friends. In his letter, Zuckerberg said all connection starts with a relationship between two people.

"Personal relationships are the fundamental unit of our society. Relationships are how we discover new ideas, understand our world and ultimately derive long-term happiness," he said. "We have already helped more than 800 million people map out more than 100 billion connections so far, and our goal is to help this rewiring accelerate."

For more, see Facebook By the Numbers: Steady Growth, Big Profits and What Facebook Fears, as well as the Facebook history slideshow below.