I have been on Flickr for a while now (since January of this year), but I still don't understand what Explore is. How do you find out if your photo is in Explore? How do other people see that your photo is in Explore? Thanks! --Grant
Explore is basically Flickr trawlling through the numerous uploads looking for 'Interesting' photos. I believe they use a combination of Comments/Views/Notes to determine what is or isn't interesting, but they won't say the exact requirments. You can use the following 3rd party link to see if you've had any photos Explored, but whatever you do; don't ask on Flickr what Explore is or how you get Explored. It's like posting the Wooden F50, or asking what people do for a living on FChat. http://bighugelabs.com/scout.php
Don't forget to check the box for "include dropped" and you will see any photos that were in Explorer but have fallen out. If you have something in explore there will be a little symbol next to it indicating rose/fell/unchanged and if you click that it will tell you how high the picture made it. In the forums on flickr there is plenty of discussion about this subject and a quick google gives links to several articles about it.