A gecko is a small lizard known for its remarkable ability to climb straight up walls and even walk upside down across ceilings. Geckos have millions of tiny hairs on their feet called setae, each ending in even tinier pads that create a weak electrical attraction to surfaces. Together, these microscopic structures let geckos stick to almost anything, from smooth glass to rough bark.

Most geckos are only a few inches long, with soft skin, large eyes, and a long tail they can drop if a predator grabs it (the tail grows back later). Unlike many lizards, geckos often have vocal abilities and make chirping or clicking sounds. Scientists have discovered over 2,000 species of geckos living in warm climates around the world, from rainforests to deserts.

The gecko's climbing ability has inspired engineers to develop new adhesives and climbing robots. Some people keep geckos as pets, particularly the leopard gecko, which has yellow skin with dark spots and doesn't require the same climbing space as species that spend more time on walls. In many tropical regions, geckos live alongside humans in houses, where they're welcomed because they eat mosquitoes and other insects.