Soil is made up of inorganic particles, sand, silt, and clay as well as organic matter, air and water.

Lightly squeeze a handful of moist soil. If the clump crumbles, the soil is sandy. If it forms a sticky ball, it's clay.

Clay soil is compromise of extremely tiny soil particles that stick together when wet and leave only a little space for air  when the soil is dry.

Sandy soil is made up of very large, slick soil particles,  so water passes through quickly.