Geocaching is a sport where participants hide a small cache and post its GPS coordinates online. Other participants follow these coordinates to find the items. The cache may contain a logbook where seekers record their names or leave comments.
Another form of geocaching is "containerless" geocaching, in which the posted GPS coordinates lead to a distinctive location or natural feature rather than a cache containing a physical item. Containerless caches do not contain logbooks for participants to sign. Geocaching is a recognized sport in the Boy Scouts of America, which offers a series of merit badges dedicated to the subject.