There are three main types of plate boundary: divergent, convergent and transform.
Plates move away from one another at divergent boundaries. This happens at mid-ocean ridges.
Plates move past on another at transform boundaries. The most famous example of this type of boundary is the San Andreas Fault in California.
Image: Cutaway artwork showing different types of plate boundary and hotspots. From left: a divergent boundary, a hotspot, a convergent boundary, and another hotspot (credit: Gary Hincks/SPL)
Iceland's volcanism is linked to its position on the Mid-Atlantic Ridge.
Professor Iain Stewart discusses Iceland's volcanoes, including the massive eruption that created the island of Surtsey in 1963. Iceland's position on the Mid-Atlantic Ridge makes it a volcanically active place.
Mount Etna has been studied for thousands of years.
Professor Iain Stewart recalls some of the ancient myths associated with Mount Etna and explains how the ancient Greeks began to take a more rational approach to the world around them. Mount Etna is an extremely active volcano that sits over a type of plate boundary known as a subduction zone.
Plate boundaries are places of chaos and mineral wealth.
Professor Iain Stewart explains how hotspots are a good demonstration of Earth's system of tectonic plates. As the plates move across the Earth's surface, they interact with one another at plate boundaries, which are places where earthquakes and volcanoes are common. Typically, plate boundaries are also places of great mineral wealth.
As well as destruction, this famous California fault brings great wealth.
Professor Iain Stewart looks at the positive side of the California San Andreas Fault, a cause of major earthquakes. The fault has made the US state rich in minerals and oil and the mountains it has formed are good for agriculture and tourism. Of course, the same fault is also responsible for loss of life and destruction of property.
Earthquakes are common at subduction zones, points where one plate moves below another.
Earthquakes are common at subductions zones, points where the Earth's plates meet and one plate moves below the other. The powerful earthquakes that are caused by this type of plate movement are known as megathrust earthquakes. The 2004 Boxing Day earthquake was a megathrust quake that triggered the subsequent deadly tsunami.
Tectonic plate interactions are of three different basic types: