Scotland is one of the four constituent countries of the United Kingdom, together with England, Wales and Northern Ireland. It is also one with the greatest number of devolved functions, has its own parliament, legal and education systems. The official currency in Scotland is, however, the same as in the whole of the U.K.: the British pound sterling, consisting of 100 pence. U.S. dollars are not accepted in Scotland apart from by some tourist attractions, which will exchange them at extremely unfavorable rates.
The exchange rate of the pound sterling to the U.S. dollar varies, but between 2009 and 2013, the official exchange rate stayed somewhere in the region of 60-to-70 pence per U.S. dollar. The actual rates you get on the ground depend not only on the official exchange rate but also the means of payment used and the type of transaction.
U.S. dollars can be exchanged at bureaux de change at the airports as well as some travel agents, retail banks and all Post Office counters. Bring a small amount of cash, around 50 or 100 pounds' worth, ideally purchased before your departure, since airport exchange rates are notoriously bad. You will, however, get a better exchange rate if you withdraw money from an ATM using a debit card. You can use your usual card from home, as long as you know the 4-digit PIN, or alternatively, buy a prepaid Visa or Master Card loaded with pound sterling before departure or at the airport. These can be used as debit cards to pay for goods as well as withdraw money from ATMs and are an excellent alternative to travelers' checks, which are now considered obsolete in Europe. Only banks will exchange them.
Although the pound sterling is the official currency of Scotland, three of the Scottish retail banks – Bank of Scotland, Royal Bank of Scotland and Clydesdale Bank – issue their own banknotes. Bank of England notes are also frequently used. This means that a visitor to Scotland is faced with what initially at least may seem like a bewildering variety of notes: four in each of the common denominations of 5, 10, 20 and 50 pounds. All of these are equivalent in value and can be used for cash purchases anywhere in Scotland. Scottish notes are commonly accepted in England, but some, especially smaller stores, may refuse them, which they have a legal right to do, so it's better to make sure that only Bank of England notes travel with you south of the border. This is even more important when leaving the U.K. altogether, since it's nigh on impossible to exchange Scottish notes outside of the U.K.
Credit and debit cards usually offer the best exchange rates for purchases, and, with both Visa and MasterCard widely accepted even in small stores and catering establishments in Scotland, using plastic when possible is the best strategy. Smaller stores may carry a surcharge for using a card for payments under 5 or 10 pounds; American Express and Diners cards are much less common in the U.K. as a whole. Large, major store chains and expensive hotels will take those, but many budget chains and smaller shops don't accept them.