Japan has a reputation for hard work, but let us assure you of one thing: it's a nation that takes its holidays just as seriously! New Year's and Obon -- the two other biggest holiday events -- only manage a single holiday each. Golden Week incorporates 3 (four, if you count "Between Day") holidays and conveniently timed weekends to make for what can only be described as a mega-holiday.
The holidays that make Golden Week golden are Greenery Day (Midori no hi), currently celebrated on April 29 (please note that in 2007, Greenery Day is moving to May 4, but Showa Day will take its place). Constitution Day (Kenpo kinenbi) hits on May 3, followed by the legal holiday Between Day (Kokumin no kyujitsu), and then Children's Day (Kodomo no hi) on May 5.
The rapid succession of holidays means that Golden Week is the perfect time for Japanese families to pack up and travel. It also means that hotels and tourists spots are very crowded. If you're traveling in the country during Golden Week, make reservations well in advance and expect large numbers of people in popular areas. All train stations and airports are packed -- be prepared.
The holidays also mean that many businesses close for the celebrations. While this is less of an issue in large cities such as Tokyo, please be aware that shops and restaurants may be closed to allow employees and owners to celebrate the days. Business travelers should plan to avoid Japan during this week altogether.
Many local jurisdictions also hold special celebrations during Golden Week.