Pinterest hit 11.7 million unique, monthly, U.S. visitors, faster than any other website on the Internet, ever.

Pinterest has been all over news sites and blogs recently for its explosive growth since the site’s inception. Even still, many have dismissed the site because they think it’s primarily a site for women. But, the latest record Pinterest has broken proves that the demographic of adult women on the Internet is nothing to shake a stick at.

comScore reported that for the first time, Pinterest hit over 10 million unique monthly U.S. visitors (11.7 million, to be precise). Why are these 10 million users more notable than the 10 million that Facebook and Google get? Pinterest hit this milestone faster than any other standalone site in the history of the Internet.

So what does that caveat mean, “standalone site”? Sites like Google+ and specific Yahoo channels got to 10 million unique monthly visitors faster than Pinterest. To be fair, comScore didn’t compare Pinterest to those sites because Google had built-in Google+ users. That means that people who already had Google accounts simply had to navigate to Google+ without signing up. The same story goes for individual Yahoo channels, accessed by say, Yahoo mail users.

On average, Pinterest users spend 98 minutes per month on the site. The only other social media sites that users stay on longer are Facebook and Tumblr. By comparison, Facebook users spend about 7 hours on the site per month, and Internet users spend about 2.5 hours per month on Tumblr. And, the stereotypes of neglected, disgruntled boyfriends holds true – Pinterest’s main demographic is 18-34 year old women in the upper middle income bracket, specifically from the Midwest.

When the news hit the Internet this morning, Formspring founder Ade Olonoh tried to show via his Google Analytics view, Formspring hit the 10 million mark in just 2 months, which made their growth faster than Pinterest.

TechCrunch, who provided the original article, got word from comScore that by their records, Formspring never reached 10 million active monthly users. The site reached just over 8 million. Of course, this is based solely on comScore data, whereas Google Analytics might take different factors into consideration and report site statistics differently.

Sure, Pinterest has over 11 million monthly users. But how do they make any money?

One blogging site called recently discovered a part of Pinterest’s back end software that the social media site hasn’t been very communicative about. When a user pins something that links back to an e-commerce website with an affiliate program, Pinterest goes into the link, adds a little bit of code that tracks what a user does next. If someone buys something from the site via that particular pin, Pinterest gets a cut of that e-commerce site’s profits.

No big deal, right? Lots of sites add tracking code to see what users do with information from their site. The real problem LLSocial had was that not once did Pinterest tell its users that this was part of the deal, not even in the terms of service agreement. Not only is it infringing on Pinterest users, but it gives the short end of the stick to the e-commerce sites it’s taking a cut of affiliate profits from.

Again, lots of websites take cuts of affiliate program profits, other companies are usually just a little more forthcoming about it. In the end, nothing Pinterest is doing is illegal, but they might go a longer way with their user base by practicing full disclosure.

In September, Pinterest had a $40 million valuation, which meant investors could get in for cheaper than the last rumored valuation estimate, which is around $200 million. And after the news this morning, that number is sure to get every larger.

We examined Pinterest in detail a few weeks ago in a case study. Check it out to find out all about how Pinterest works and how the company makes sure it has a tech system in place to keep up with the amazing amount of growth it’s already received.