Noctilucent Cloud (NLC) is an unusual and intriguing phenomenon of the Earth's upper-atmosphere. They are most often seen at times close to the summer solstice, when they appear against the backdrop of deep, evening twilights. This site provides an introduction to NLC and outlines the methods and techniques used to observe and report  them.  The site also acts as a reporting location for Internet users, allowing an exchange of information as each NLC season progresses, providing  instantly updated tables of sightings.  Visitors are invited to contribute any such material and participate in the site's ongoing work.