Before you purchase any travel insurance, it is a good idea to review existing policies and agreements with credit card companies because certain things, such as lost luggage and car rental liability, may be sufficiently covered, especially for short or domestic trips. Travelers should also familiarize themselves with cancellation policies of most hotels, tours cruise lines or other travel service providers. Reviewing their existing coverage also provides useful information on the types of policies that may be needed. Most travel insurance can be purchased on either a per trip or annual basis, just choose what you prefer. The U.S. Travel Insurance Association (UStiA) notes that more than 80% of travel insurance purchased by Americans is purchased on a per trip basis and covers trip cancellation; interruption; travel or baggage delay; stolen, lost,damaged baggage; medical expenses and medical evaluation expenses. To those who travels more frequently they may want to consider purchasing an annual plan which typically includes medical and medical evacuation coverage because such services are generally not covered by most health maintenance organization (HMO) policies if they occur out-of-area, even if they occur domestically.