At the very basic definition, a factory farm is usually a large industrial facility where livestock are crowded together.
Technically, factory farms are known as Concentrated (or Confined) Animal Feeding Operations (CAFOs): Defined by the Environmental Protection Agency (EPA) as “New and existing operations which stable or confine and feed or maintain for a total of 45 days or more in any 12-month period more than the number of animals specified.” Also the EPA notes that factory farms have, "No grass or other vegetation in the confinement area during the normal growing season.”
Looking further into the problem, factory farms often have animals living in unsanitary conditions with little access to nature, fresh air or sunlight. Livestock at outdoor factory farms are often forced to live in their own waste and mud, without shade or shelter. Animals on factory farms may even be mutilated.
For humans, factory farms pose a risk as well. Factory farming can create public health problems due to excessive antibiotic use. Sustainable Table notes that property values of houses near factory farms decrease.
Organic certification of livestock farms helps eliminate many of the above problems, as there are strict rules about antibiotic use and access to pasture policies. Furthermore, organic livestock farmers practice a much more hands-on approach to animal care.
Take a scary in-depth look at what goes on at factory farms.