(MONEY Magazine) – Every frequent traveler knows that if you often fly the same airline, stay at the same hotel chain or rent from the same car agency, you'll be rewarded for your loyalty with miles or points good for free flights, rooms and cars. What may be less familiar are the alliances among the country's largest airlines, hotel chains and car-rental agencies shown in the tables at right. (Southwest is not included because it has only two partnerships, with Budget and Hertz.) If you stay at a Marriott, for example, you can earn United frequent-flier miles. Rent a car at Avis and you can pay with Best Western loyalty points. In most cases, when you rent a car or stay at a hotel, you can earn points or miles for only one program. Hilton is an exception; you can earn both miles and Hilton HHonors points.

Restrictions and caveats abound. Sometimes you'll earn airline miles for a hotel stay or car rental only if you've flown that airline in the preceding 24 hours. Often, you have to convert points into award certificates, which takes time. For details, contact the programs. (See "Toolbox," on the facing page.)

Finally, don't overlook airline-to-airline and hotel-to-hotel alliances. At six major hotel chains owned by Starwood, including Sheraton and Westin, you can earn points good at any Starwood hotel. And six domestic airlines have paired off to let frequent fliers earn or redeem miles on each other's flights. --JUDY FELDMAN

THE MAJOR PLAYERS HOTELS Best Holiday Western Hilton Inns Hyatt Marriott Radisson Sheraton Westin

AIRLINES

Alaska [*] [*] [*] [*] [*] [*] American [*] [@] [@] [@] [@] [@] [@] [@] America West [*] [*] [*] [*] [*] [*] [*] Continental [@] [*] [*] [*] [*] [*] [*] Delta [*] [@] [*] [*] [*] [*] [*] [*] Northwest [*] [*] [*] [*] [*] [*] [*] Trans World [@] [*] [*] [*] Airlines United [@] [*] [*] [*] [*] [*] [*] US Airways [*] [*] [*] [*] [*] [*] [*]

CARS

Avis Budget Hertz National [AIRLINES]

[Alaska] [*] [*] [*] [American] [@] [@] [@] [@] [America West] [*] [*] [Continental] [*] [*] [*] [Delta] [*] [*] [*] [Northwest] [*] [*] [Trans World [*] [*] [*] Airlines] [United] [*] [*] [*] [*] [US Airways] [*] [*]

HOTELS

Best Western [#] [#] Hilton [#] [#] Holiday Inns [#] Hyatt [#] Marriott [#] Radisson Sheraton [#] Westin [#]

How to read this table

[*] Earn airline miles from hotel stays or car rentals [@] Earn airline miles from hotel stays or car rentals and redeem airline miles for hotel stays or car rentals. [#] Earn hotel points from car rentals and redeem hotel points for car rentals.

AIRLINE ALLIANCES

American [~] US Airways Continental [^] [~] Northwest Delta [~] [^] United

How to read this table

[^] Fly one airline and earn miles in the partner airline's program [~] Redeem miles from one program for a ticket on the other airline.