Collieries are mines where coal is extracted from the ground. There are numerous synonyms for this word, including coal mines, coal pits, coalfields, coal seams, and coal hollows. Other words used to describe collieries include drift mines, slope mines, underground mines, and strip mines. These synonyms apply to different types of mines depending on the method of extraction, location, and type of coal being mined. Collieries were once a dominant feature in the landscape, providing heat and energy for homes, businesses, and industries. Although many collieries have closed over the years, the legacy of these coal mines can still be seen in towns and villages that grew around them.