Facebook makes a major move.

Facebook this afternoon filed for an initial public offering that paves the way for all investors to own stock in the world’s largest social network. Here are the top-line details:

Offering size: Facebook says it plans to raise $5 billion. Some pundits have suggested this is a major decrease in Facebook’s ambitions, due to earlier press reports that the company would seek $10 billion. Two points: (1) Those original reports may have been wrong, and it’s absurd to say a company resized something it had never officially sized in the first place. (2) Offering amounts on S-1 documents sometimes are more placeholders than anything else. For example, The Carlyle Group is expected to raise billions — but filed to raise just $100 million.

Valuation: Companies rarely disclose anticipated share price details in S-1 filings, and Facebook is no different. Reports are that the company will seek a valuation of between $75 billion and $100 billion, but we have no idea until it amends its filing.

Financials: Facebook reports $3.71 billion in 2011 revenue, and $1 billion in net income. This is in line with what we’d previously learned from leaked financials. In other words, no Google surprise. The company also reports around $3.9 billion of cash on hand at the end of 2011.

Shareholders: Mark Zuckerberg is Facebook’s largest single shareholder, and also controls the voting rights. Other major holders include Accel Partners, DST Group, T. Rowe Price and Goldman Sachs.

Banks: As expected, Morgan Stanley MS  got the coveted “lead left” position. J.P. Morgan and Goldman Sachs GS also got top-line billing, while BoA Merrill Lynch BAC , Barclays Capital and Allen & Co. filled out the underwriting syndicate.

The letter: As is customary with every major tech IPO since Google GOOG , Facebook includes a letter to prospective shareholders from its CEO. Perhaps the most important line: “We don’t build services to make money; we make money to build better services.”

Listing: Facebook will trade under ticker symbol FB. No decision yet on NYSE or NASDAQ.

Compensation: Zuckerberg made a base salary last year of $500,000. His total compensation for last year was around $1.5 million. COO Sheryl Sandberg and CFO David Ebersman each pulled down $300,000 in base salary, but $30.8 million and $18.7 million, respectively, in total comp.

Shareholder Liquidity: I was really hoping that this filing would let us know how much money insiders, including Zuckerberg, have taken off the table so far. No such luck. There is mention of Morgan Stanley buying some insider shares in 2010 and 2011, but no specifics. This is in stark contrast to the Zynga GRPN and Groupon GRPN registration docs, which explicitly spelled out how much had been sold and by whom. That said, we know that Accel Partners and Dustin Moskovitz have both sold Facebook shares on the secondary market. One source (and I stress, it is only one source) says that Zuckerberg never sold shares on the secondary market.

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