Final answer:
Magma that reaches the surface through a volcano is called lava, an event most common in volcanic regions marked by specific geological features such as mid-ocean ridges and subduction zones, forming igneous rocks.
Step-by-step explanation:
When magma reaches the surface by erupting through a volcano, it is called lava. This process occurs in volcanic regions, where the characteristics for an ideal site for magma to emerge include fractured rock above the magma allowing water flow, water temperatures in excess of 180°C (under pressure), and a caprock that traps pressurized steam. Volcanoes are geological features that mark locations where lava rises to the surface and can form at mid-ocean ridges, subduction zones, or even due to hot spots caused by mantle plumes. When lava flows from a volcano and hardens, it forms igneous rock. The volcanic activity gives us a glimpse into the material from deep within our planet, which is not only essential to understanding Earth's geology but also contributes to the formation of igneous rocks.