Prescription is when a person obtains a legal right through the repeated use of something without complaint from an owner. Typically, prescription applies to real property. Also, prescription usually grants a right to use certain portions of a person's property, not to own it. The length of time that a person must use another person's land without complaint from the owner varies from state to state in order to get prescription.
Prescription is often used in situations where one neighbor has been using the land of another neighbor as a shortcut for years. For example, if one farmer has been cutting through his neighbor's farm for five years, he may be granted prescription. Upon the granting of prescription, the farmer would be able to legally cut through the neighbor's yard to get to his own. The farmer would not own the land, but would just be able to use it like he had been doing all along. The difference is that now it would be legal.