Customs

If you plan to take any new, non-U.S.-made articles of value, such as cameras, computers, bicycles, electronic devices or jewelry that are less than six months old, you should register them with U.S. Customs and Border Protection before departure (CBP Form 4457). Alternately, you can carry your original sales receipts to prove that you purchased them in the U.S. This avoids you having to pay a duty upon your return.  Customs regulations vary from country to country; there are usually limitations on liquor, cigarettes, and other goods.