Neither the tenant nor the landlord can unilaterally change the terms of the lease during the lease term. The lease represents a contract that both the tenant and the landlord have agreed to abide by for its full term. However, the tenant and the landlord are always free to negotiate and reach a modification of the lease that is acceptable to both. At the expiration of the existing lease, both the landlord and the tenant are free to refuse to sign a new lease unless new terms, more to that party's liking, are agreed to. If the landlord refuses to make a tenant's requested changes, the tenant is free to move away and do business with someone whose terms are more to the tenant's liking. If the tenant refuses to make a landlord's requested changes, the landlord is free to find a new tenant whose terms are more to the landlord's liking. There is an important exception to this general rule. Many leases provide that the landlord has the right to promulgate rules and regulations for an apartment community and can change those rules upon notice to the tenant (usually thirty days) even during the term of the lease. Consequently, many tenants have contractually given the landlord the right to make some changes to the terms of the parties' agreement before the lease expires.