Tokyo officially Tokyo Metropolis is one of the 47 prefectures of Japan and located on the eastern side of the main island Honshū. The twenty-three special wards of Tokyo, each governed as a city, cover the area that was once the city of Tokyo in the eastern part of the prefecture, and total over 8 million people. The population of the prefecture exceeds 12 million. The prefecture is the center of the Greater Tokyo Area, the world's most populous metropolitan area with 35 million people.

Tokyo is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family.

The mainland portion of Tokyo lies northwest of Tokyo Bay and measures about 90 km east to west and 25 km north to south. Chiba Prefecture borders it to the east, Yamanashi to the west, Kanagawa to the south, and Saitama to the north. Mainland Tokyo is further subdivided into the special wards (occupying the eastern half) and the Tama area stretching westwards.

Also within the administrative boundaries of Tokyo Metropolis are two island chains in the Pacific Ocean directly south: the Izu Islands, and the Ogasawara Islands, which stretch more than 1,000 km away from mainland Japan. Because of these islands and mountainous regions to the west, Tokyo's overall population density figures far underrepresent the real figures for urban and suburban regions of Tokyo.

Under Japanese law, Tokyo is designated as a translated as metropolis. Its administrative structure is similar to that of Japan's other prefectures. Within Tokyo lie dozens of smaller entities, most of them conventionally referred to as cities. It includes twenty-three special wards which until 1943 comprised the city of Tokyo but are now separate, self-governing municipalities, each with a mayor and a council, and having the status of a city. In addition to these 23 municipalities, Tokyo also encompasses 26 more cities , five towns , and eight villages , each of which has a local government. The Tokyo Metropolitan Government is headed by a publicly elected governor and metropolitan assembly. Its headquarters are in the ward of Shinjuku. They govern all of Tokyo, including lakes, rivers, dams, farms, remote islands, and national parks in addition to its famous neon jungle, skyscrapers and crowded subways.

Tokyo lies in the humid subtropical climate zone (Koppen climate classification Cfa), with hot humid summers and generally mild winters with cool spells. Annual rainfall averages 1,380 mm (55 inches), with a wetter summer and a drier winter. Snowfall is sporadic, but does occur almost annually. Tokyo is an example of an urban heat island; the city's population is a significant contributor to its climate. Tokyo has been cited as a "convincing example of the relationship between urban growth and climate". Tokyo also often sees typhoons each year, though few are strong. The last one to hit was Fitow in 2007.

Tokyo was hit by powerful earthquakes in 1703, 1782, 1812, 1855 and 1923. The 1923 earthquake, with an estimated magnitude of 8.3, killed 142,000 people.

Tokyo has many museums. In Ueno Park are four national museums: Tokyo National Museum, the country's largest museum and specializing in traditional Japanese art; the National Museum of Western Art; and the Tokyo National Museum of Modern Art, with its collections of Japanese modern art as well as over 40,000 Japanese and foreign films. Also in Ueno Park are the National Museum of Science and the public zoo. Other museums include the Nezu Art Museum in Aoyama; the Edo-Tokyo Museum in Sumida across the Sumida River from the center of Tokyo; and the National Diet Library, National Archives, and the National Museum of Modern Art, which are located near the Imperial Palace.

Tokyo has many theaters for the performing arts as well. These include national and private theaters for traditional forms of Japanese drama (like noh and kabuki) as well as modern dramas. Symphony orchestras and other musical organizations perform Western and traditional music. Tokyo also hosts modern Japanese and Western pop and rock music at venues ranging in size from intimate clubs to internationally known arenas like the Nippon Budokan. Many different festivals occur throughout Tokyo. Major events include the Sannō at Hie Shrine, the Sanja at Asakusa Shrine, and the biennial Kanda Festivals. The last features a parade with elaborately decorated floats and thousands of people. Annually on the last Saturday of July, an enormous fireworks display over the Sumida River attracts over a million viewers. Once cherry blossoms, or sakura, bloom in spring, many residents gather in Ueno Park, Inokashira Park, and the Shinjuku Gyoen National Garden for picnics under the blossoms.

Harajuku Station on the Yamanote Line in the Shibuya ward of Tokyo is known internationally for its youth style and fashion.

Cuisine in Tokyo is internationally acclaimed. In November 2007, Michelin released their guide for fine dining in Tokyo, garnering 191 stars in total, or about twice as many as its nearest competitor, Paris. Eight establishments were awarded the maximum of three stars (Paris has 10), 25 received two stars, and 117 earned one star. Of the eight top-rated restaurants, three offer traditional Japanese fine dining, two are sushi houses, three serve French cuisine. Sports in Tokyo are diverse. Tokyo is home to two professional baseball clubs, the Yomiuri Giants (Tokyo Dome) and Yakult Swallows (Meiji-Jingu Stadium) . The Japan Sumo Association is also headquartered in Tokyo at the Ryōgoku Kokugikan sumo arena where three official sumo tournaments are held annually (in January, May, and September). Football (soccer) clubs in Tokyo include F.C. Tokyo and Tokyo Verdy, both of which play at Ajinomoto Stadium in Chōfu. Tokyo hosted the 1964 Summer Olympics. National Stadium, also known as Olympic Stadium, Tokyo is host to a number of international sporting events. With a number of world-class sports venues, Tokyo often hosts national and international sporting events such as tennis tournaments, swim meets, marathons, American football exhibition games, judo, karate, etc. Tokyo Metropolitan Gymnasium, in Sendagaya, Shibuya, is a large sports complex that includes swimming pools, training rooms, and a large indoor arena. Tokyo is one of the cities bidding to host the 2016 Summer Olympics.