Hashtags are used to categorize messages in Pinterest comments and descriptions. You simply put the # symbol right in front of keywords or topics in your comments without leaving a space between the # and the word, or between the words themselves, as shown in Figure 5.2. Tagging helps people find your pins and boards. Some popular hashtags from Pinterest include #infographics, #wedding, and #recipes. You can come up with your own hashtag, or use ones that you see in Pinterest.
When you use a hashtag, the # sign and the word following it become a link on which users can click to get to similar pins. When you click on #recipes, for instance, users will be taken to a page of current recipes in Pinterest (with the most current ones at the top of the page).
As Pinterest grows, I believe they will expand their usage of hashtags, and make their search function better. For now, you can use hashtags to denote the general topic of your pin and to find other similar pins.