Nantucket is an island ruled by the Commonwealth of Massachusetts, USA. It has a year-round fishing industry, but it mostly thrives on tourists, due to:
Nantucket mostly has beaches. Lots and lots of beaches. They are manned Memorial Day - Labor Day, but there's nothing to stop you from enjoying them all year. There are also some preserved highlands on the island; they may not be as spectacular as the beaches, but due to the windy island climate, they're more unique. What trees you see there, can tolerate the high salt content of the wind.
Nantucket also has a couple of museums, commemorating the island's main industries other than tourism: whaling and basket-making. There are many historic buildings, such as the island's oldest building and the island's old jail, which are also open to tourists. The whaling museum is open year-round, but only on Saturdays outside the main tourist season. Otherwise, tourists are most likely to find their attraction open Memorial Day - Labor Day.
Nantucket is roughly 14 miles long and 4 miles thick. It is home to 7,000 people in the winter and 50,000 in the summer. Most of these live near Nantucket harbor, in the village of Nantucket.
For other villages: Check the ^%$#@!ing map.
Nantucket is windy. The island is relatively flat, which prevents the wind from stopping. There aren't a lot of trees there, because the wind tends to blow them over. However, many private residences have their own windmills. Nantucket is currently debating the use of windmills on a large scale, to provide island-wide power.
Nantucket is spectacular to look at. Many private residences have their own "crow's nests", which are walkways on top of the house where the residents may look out at the sea. (These house features are also known as "widow's walks".)
Nantucket is boring, at least if you live there full time. It is said to have the highest rate of Driving While Intoxicated accusations in Massachusetts.
To get onto Nantucket, one must first get onto either Cape Cod or Martha's Vineyard. These are problems in and of themselves, due to their both being islands. Cape Cod is a man-made island, thanks to the Cape Cod Canal; there are only two bridges onto or off of the Cape. These bridges get very crowded in summer. But once one gets onto the Cape, it is the best staging point for Nantucket.
The heavy-duty government-operated ferry (www.islandferry.com) comes to Nantucket from Hyannis three times a day, all year; there are substantially (how many?) more ferries in summer. The ferry takes 2:15 hours each way, though it may run 15 minutes over sometimes. Automobiles cost $105 USD to bring to the island one-way off-season, $165 on season (as opposed to $13 for a passenger and $5 for a bike each way).
There are other ferries which operate during tourist seasons only. One such, the ??, takes only one hour from Hyannis, but it takes passengers (and bicycles?) only. Another ferry operates from Martha's Vineyard (another Massachusetts island, which belies the problem of getting onto the islands in the first place), but only during tourist season.
One may also take an airplane from Hyannis. Airplanes make the trip 10 times a day, all year. The trip takes 12 minutes.
There are several tips which a cheap tourist may take:
Nantucket has a substantial population of migrant workers, especially in the construction industry, who do the day trip.