Every lease or rental agreement should identify the “parties” to the agreement. These typically include all landlords and tenants, and any cosigners.
Landlord or the property owner. If you are using a business name, enter your name, followed by your business name.
All adults who will live in the rental premises, including both members of a couple (married or unmarried. Having everyone (except minor children) sign your lease or rental agreement makes each person a cotenant, with the same rights and responsibilities for paying the rent, taking proper care of your property, and complying with other terms of your agreement. Failing to have everyone sign the lease can cause landlords many legal problems: You may end up with too many occupants or overcrowding (perhaps in violation of health and safety codes) and/or people you have not screened properly. If a resident who is not a legal tenant causes problems, you may have trouble evicting them, depending on how long the person has lived in the rental, whether or not you have treated them as a lawful tenant (by accepting rent, for example), and other factors.
Cosigners. Some landlords require cosigners, or guarantors, to sign a lease or rental agreement (this may be part of the lease itself, or a separate document attached to the lease). Cosigners are common if you are renting to students who depend on their parents for rent money. The cosigner agrees to be “jointly and severally” liable with the tenant for the tenant’s obligations under the lease or rental agreement—for example, to cover any rent or the cost of repairing any damage the tenant causes.