What is the term used for underground layers of rock that store and transmit groundwater?

At some places ground water is stored between layers of hard rock below the water table. This is known by which name?

What is the main source of groundwater recharge?

Which type of rock formation is most commonly associated with low groundwater storage?

All space between particles of soil and gaps between rocks are filled with water; the upper limit of this layer is called:

A geographical unit that collects, stores and release water is called -