Explore is a function of Flickr where amongs all the photographers that sends pictures to the site a few are selected (500 to be precise) on each day to be included in a kind of hall of fame called the Explore.
The exact criteria for when pictures are included is not known, in fact it is a well kept secret for it is fine-tuned all the time, if you have been in explore many times it gets harder to become picked, if you send a photo to many groups it can be harder but also the number of views, comments, fave markings you get contribute to your Explore score.
1. It was a fabulous moon, 2. Where I am going, 3. The Night Watch, 4. The Small House, 5. The Cat, 6. Grödinge church infrared, 7. Ghost in the Window, 8. Kapelludden Cross, 9. A Second in Life, 10. Pompom and the Sea, 11. DSC_1355, 12. Polished Metal, 13. The Sky and the Snowcovered Lake, 14. Fluxfallet, 15. Strokkur, 16. Fontain Rainbow