Foliation is a geological process that occurs in certain types of metamorphic rocks, where minerals are aligned in parallel layers or bands. This alignment happens due to intense pressure and temperature conditions, causing the minerals to recrystallize and form distinct planes. Common examples of foliated rocks include slate, schist, and gneiss. The presence of foliation can significantly affect the physical properties of the rock, such as its strength and how it breaks. Foliated rocks often split easily along the planes, making them useful for various applications, including construction and decorative stonework.