Lava tubes and caves, when accessible for man, are very common in volcanic environments and poorly known to non-specialists. This short overview presents the distribution and forms of lava tubes, their speleothems and mineralogy and modes of formation. Studies of lava caves outside of Earth currently are a topic of great interest, as they may be potential locations for some life forms and future bases in space exploration. Basic features of lava tubes are illustrated with reference to the longest lava cave in the world, Kazumura Cave, in Hawaii.