In addition to the basics of a rental (who, what, when, how much), an apartment rental may go into much more detail on these and other issues.

Who: is the renter living alone, with family, children, room-mate, visitors? An apartment rental may delineate the rights and obligations of each of these. For example, a sublet; to a stranger might not be permitted without permission of the landlord. On the other hand, the renter may also have specific rights against intrusions by the landlord (or other tenants), except under emergency circumstances. A renter is in possession of the property, and a landlord would be trespassing upon the renter's rights if entry is made without proper notice and authority (e.g., 24 hours' notice, daytime, knock first, except for emergency repairs, in case of fire, flood, etc).
What: the rental apt rented may include not only specific rooms, but also access to other common areas such as off-street parking, basement or attic storage, laundry facility, pool, roof-deck, balconies, etc. The agreement may specify how and when these places may be used, and by whom. There may be detailed description of the current condition of the rental apt, for comparison with the condition at the time the rental apartment are surrendered.
When: the term of the apartment rental may be for a night (e.g., a hotel room), weeks, months, or years. There may be statutory provisions requiring registration of any rental that could extend for more than a specified number of years (e.g., seven) in order to be enforceable against a new landlord.
A typical apt rental is either annual or month-to-month, and the amount of rent may be different for long-term renters (because of lower turnover costs). Leaving a long-term lease before its expiration could result in penalties, or even the cost of the entire agreed period (if the landlord is unable to find a suitable replacement tenant, after diligent pursuit). If a tenant stays beyond the end of a lease for a term of years (one or more), then the parties may agree that the lease will be automatically renewed, or it may simply convert to a tenancy at will (month-to-month) at the pro-rated monthly cost of the previous annual lease. If a tenant at will is given notice to quit the rental apartment, and refuses to do so, the landlord then begins eviction proceedings. In many places it is completely illegal to change locks on doors, or remove personal belongings, let alone forcibly eject a person, without a court order of eviction. There may be strict rules of procedure, and stiff penalties (triple damages, plus attorneys' fees) for violations.
How much: Rent may be payable monthly, annually, or in advance, or as otherwise agreed. A typical arrangement for tenancy at will is "first and last month's rent" plus a security deposit. The "last month's rent" is rent that has yet to be earned by the landlord. The security deposit is often handled as an escrow deposit, owned by the tenant, but held by the landlord until the rental apartment are surrendered in good condition (ordinary wear and tear excepted). In some states, the landlord must provide the tenant with the name and account number of the bank where the security deposit is held, and pay annual interest to the tenant. Other regulations may require the landlord to submit a list of pre-existing damage to the property, or forfeit the security deposit immediately (because there is no way to determine whether a prior tenant was responsible).
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Rental Agreement".