A landlord when making an important lease may properly require that the tenant furnish security for the performance of the terms of the lease. This security may be in the form of cash or negotiable securities or it may be in the form of a bond executed by personal sureties or a surety company. There is no rule as to the amount of the security, but it is usually in proportion to the amount of rent reserved by the lease. The security may be a sum equal to the rent for one month or several months, or even a year or more. It is often agreed that the tenant shall receive interest at a certain rate on cash security deposited by him.