Why Don't House Lizards Fall Off the Wall?

At night, small house lizards are often seen crawling on the wall to catch mosquitos. Sometimes they even crawl on the ceiling. Why don't they fall off the wall or the?

Small house lizard has very special hooked feet with a sucker. The sucker to be like a magnet that slicks to the wall tightly. That's why ,they don't fall off the wall.