AIRPORT TAX This is invariably included in the price of your ticket.

CIGARETTES AND SMOKING The country that first gave tobacco to the world is now probably the most concerned about its detrimental effects on health. Smoking is generally frowned upon - though many Americans still smoke. Most cinemas are nonsmoking, restaurants are usually divided into nonsmoking and smoking sections (California and New York City have banned smoking altogether in most restaurants) and smoking is forbidden on public transportation and flights.

DATES In the American style, the date 1.8.02 means not 1 August but January 8.

ELECTRICITY 110V AC. All plugs are two-pronged and rather insubstantial. Some travel plug adapters don't fit American sockets.

FLOORS The first floor in the US is what would be the ground floor in Britain; the second floor would be the first floor, and so on.

ID : Should be carried at all times. Two pieces should suffice, one of which should have a photo: a passport and credit card(s) are your best bets. Not having your license with you while driving is an arrestable offense.

MEASUREMENTS AND SIZES US measurements are in inches, feet, yards and miles, and weights in ounces, pounds and tons. American pints and gallons are about four-fifths of Imperial ones. Clothing sizes are four figures less what they would be in the UK - a British women's size 12 is a US size 8 - while British shoe sizes are 1/2 below American ones for women, and one size below for men.

TAX A sales tax is added to virtually everything you buy in a shop, but isn't included in the marked price. The actual rate varies from place to place: in New York and parts of California it's above eight percent, while some states - Alaska, Delaware, Montana and Oregon - have no sales tax at all. A hotel tax will add five to fifteen percent to most bills. You also often must pay a tax on top of the cost of a car rental if you pick up the vehicle at an airport.

TEMPERATURES Always given in Fahrenheit.

TIPPING Expected for all bar and restaurant service, at a rate of fifteen to twenty percent or so on the bill (unless the service is utterly abominable). About the same amount should be added to taxi fares. A hotel porter who has lugged your suitcases up several flights of stairs should get $3 to $5.

VIDEOS The standard format used for video cassettes in the US is different from that used in the United Kingdom, Ireland, Australia, New Zealand, and elsewhere. This means that you cannot buy prerecorded videotapes in the US compatible with a video player bought in another country. However, blank tapes in the US can be used with cameras bought elsewhere as the camera will format the tape to record and play in the correct standard.