The Illustration above shows an illustration of a Room & Pillar Mine. Room and pillar mining is still very common in underground coal mines, because it is very flexible and does not require a large capital expenditure for equipment like a longwall mining operation would.
Room & Pillar is so named, because pillars of coal are left standing to help support the roof of the mine. A typical design would have the entry ways ( or rooms) with a width of 20 feet, and the pillars with width's of 40-60 feet.
In some room & pillar mines, on retreat mining, the pillars are removed, allowing the roof to collapse. This is called "pulling the pillars".

While a longwall section would have production rates of 1,000 to 20,000 tons per shift, room and pillar mines have lower production rates of 600 to 1,000 tons per shift per miner unit.

Photo is a Continuous Miner machine, commonly used in coal room and pillar mining. These miners can achieve production rates up to 1,000 tons per shift. The rotating bits on the drum rip the coal from the seam and it is gathered by rotating arms and transported to a haulage vehicle by a chain conveyor.