Pinterest on Monday said it will soon start pinning ads to its popular online bulletin boards. Advertising in the form of "promoted pins" will begin appearing on Pinterest pages in the coming months, the California startup said in reply to an AFP inquiry. Pinterest began testing promoted pins late last year and is "encouraged" by what it has so far seen, a company spokeswoman said. Facebook and Twitter both bring in money from ads in the form of posts "promoted" to prominent positions in streams of updates at the social networks. Pinterest late last year raised $225 million in new capital that it planned to use to expand to 10 more countries. The funding round valued the company at $3.8 billion, according to a Pinterest statement to AFP. Co-founder and chief executive Ben Silbermann said the new funding will help Pinterest's expansion. Pinterest has become one of the Internet's hottest young websites, particularly among women, by giving people virtual bulletin boards that they can decorate with pictures showcasing interests in anything from food to sports, to fashion or travel. The company has not disclosed the number of users, and analyst estimates vary widely from 30 million to 70 million.