Over the past 8 months I have been trying to analyze the importance of tagging my photos properly when posting to Tumblr. Well, come to find out not only is it important, it is of PINNACLE importance. Things I found during this analysis: Nearly 100% increase in traffic: 896 visitors on untagged photos compared to 1,840 average for properly tagged photos Of visitors to properly tagged photos 95% were NEW visitors who came through the Tumblr search. New visitors stayed on page average of 18 minutes, compared to a little less than 4 minutes by returning visitors. So basically tag your photos well, and the snowball effect will get rolling over the months.