What is the main purpose of Pinterest?
Pinterest is basically a pinboard - that is, you go on it to 'pin' things of interest that you want to share, just as you might put up a picture or news cutting on a pinboard in your kitchen. People put photographs, mainly with a theme - for example, of things they have collected.
Most of Pinterest's users are women, though the site was actually created by a man (Ben Silverman) in 2009. It wasn't created specially for women and it is open to everyone, this is just the way things have developed. A lot of the image collections are to do with things like cookery, jewellery and home decoration that may attract more female viewers, but as the site is still growing fast it could all be different a year from now.
It's also a commercial site, as there is a section where you can buy gifts, so that is another purpose of Pinterest.