In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body. In most common usage, the term is used for the approximately circular depression in the surface of a planet, moon or other solid body in the Solar System, formed by the hypervelocity impact of a smaller body with the surface. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is perhaps the best-known example of a small impact crater on the Earth.

Impact craters are the dominant landforms on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. On other planets and moons that experience more-active surface geological processes, such as Earth, Venus, Mars, Europa, Io and Titan, visible impact craters are less common because they become eroded, buried or transformed by tectonics over time. Where such processes have destroyed most of the original crater topography, the terms impact structure or astrobleme are more commonly used. In early literature, before the significance of impact cratering was widely recognised, the terms cryptoexplosion or cryptovolcanic structure were often used to describe what are now recognised as impact-related features on Earth.

The Walls are an Irish rock band. They were formed in 1998 by two ex-members of The Stunning.

Brothers Steve and Joe Wall (previously of The Stunning) returned to Ireland after a two-year failed label stint in London. Their Camden housemate Carl Harms joined the band on guitar and keyboard duties. Drummer Rory Doyle joined soon afterwards. They set up their own label, Earshot Records (later changing it to Dirtbird Records) and recorded and released a string of singles. A remix of one of the album tracks, "Bone Deep", clicked with radio and became a nationwide hit. Many of the songs have featured on a number of TV series and feature films such as Bachelors Walk, Dead Bodies, Goldfish Memory and On the Edge (starring Cillian Murphy).

The Walls heard rumour of a second Slane Castle date for U2 (as the first concert had sold out in hours). They sent four copies of their album to the band. Bono loved it and offered The Walls a support slot. That day the band played to their biggest crowd to date – around 80,000 people. "To the Bright and Shining Sun" was their next single. That June they supported Red Hot Chili Peppers. They spent the next year gigging while building their own studio in Dublin.