Social networking service based on the image Pinterest have loosened policy, by opening the site to the public.
Previously, a person must first be invited to become members and "put" (pin) to an online photo site.
Launched in 2010, Pinterest become the fastest growing websites, with users reach 10 million within nine months.
Despite efforts to increase revenue, the company has not announced plans to sell.
"They are one of the great sites that cater to the so-called social collectors, people who like to gather information from the site," said Forrester Research analyst Darika Ahrens.
"What we have to monitor is when they begin to commercialize themselves - how they would do and whether they do it in a way that does not make them feel alienated users.
"So far they have tried a number of different methods such as using a commercial link that can make money, but they've stopped doing it."
One media analyst told the BBC saying that Pinterest have a marketing strategy by inviting users.
"Tactics to use exclusivity in launching a social network, not a new thing," said Rob McNair of mycleveragency.com.
Fashion and recipe quickly became a major topic in Pinterest, and the number of users a lot more women on this site.
The number of users is increasing quite rapidly over the last year, according to analyst firm comScore digital media.
Data were mentioned, in June, there were about 1.2 million users globally - a year later to 31.2 million.
In February, the company has stated kekhawatiranna of copyright to the material used by the user.
Now the site can look at Pinterest. With it, the site can block content by adding their site code.
If a user Pinterest try to share pictures or other material to the site without the instruction "nopin", it will display the message: "This site is not allowed to put in Pinterest. Please contact the owner. Thank you for your visit".