There are many agricultural mitzvos in EretzYisroel which revolve around a seven-year cycle. The seventh year of this cycle is called Shemitta. A year of Shabbos – rest for the land.
During the Shemitta year, there is a prohibition to work the land which is left to rest and is treated with special status. Produce that grows during this year is considered hefker - ownerless. In addition, produce from the Shemitta year attains an elevated status of sanctity, kedushasshevi’is, which places additional restrictions on the way the produce is to be treated.
At the end of the Shemitta year, some debts are liable to be cancelled and it is customary to write a pruzbul (see below) to avoid the need to annul debts