Silo are needed for holding bulk materials like grain and fermented silage feed. Commonly they are also used to store in bulk the likes of coal, cement, sawdust and food products. Silos are often thought of as a coffee thermos since they are tall, skinny and seal completely tight to hold in moisture – which makes them ideal for grass or other fodder which is harvested green and wet and needed to feed cattle. Depending on their purpose, there are three types of silos which include tower silos, bunker silos and bag silos. Silos are predominately used in agriculture to store food needed to feed animals. They are most agriculturalists go-to for grain and fermented silage feed.