As of February 2017, the city has an estimated population of 720,841 and a population density of 910 persons per km². The total area is 789.88 square kilometres.
The city is the site of Kōraku-en, known as one of the top three traditional gardens in Japan, and Okayama Castle, which is ranked among the best 100 Japanese castles. The city is famous as the setting of the Japanese fable "Momotarō".
Before the Muromachi period, Okayama was one corner of a farm region and included a small castle built by the Kanemitsu. In the Sengoku period, Ukita Naoie attacked Okayama and attacked the castle for the transportation resources and extensive farmland in the region. Naoie remodeled the castle, built the old Sanyo road to the central part of the castle town, and called in craftsmen both from inside and outside of Bizen Province. Okayama became the political and economical capital of Bizen Province.
In 1600, Ukita Hideie, who was the son of Naoie and the lord of Okayama, lost at the Battle of Sekigahara. The next year, Kobayakawa Hideaki came to Okayama and became the feudal lord of Okayama Domain. Hideaki died in 1602, however, ending the Kobayakawa line. Ikeda Tadatugu, who was the feudal lord of Himeji Domain, became the next lord of Okayama. After this time, Okayama was ruled by the Ikedas until the latter part of the 19th century. Continuing its economic development, Okayama became one of the ten best large castle towns in Japan in the 18th century. The Korakuen Garden was developed by the fourth feudal lord, Ikeda Tsunamasa.
On August 29, 1871, the new Meiji government of the Empire of Japan replaced the traditional feudal domain system with centralized government authority (Prefectures of Japan). Okayama became the capital of Okayama Prefecture. In 1889, Okayama City was founded. In the Meiji period, a railroad was built in Okayama city that greatly enhanced the development of the city. For example, the Sixth Higher Middle School (第六高等学校, Dairoku Kōtōgakkō) and Okayama Medical College (岡山医科大学, Okayama Ika-daigaku) were established in Okayama City. Okayama became one of the most important places in western Japan for transportation and education. When World War II began, Okayama city had a Japanese Army base camp. On June 29, 1945, the city was attacked by the US Army Air Forces with incendiary bombs. Almost all the city was burned, and more than 1700 people were killed. Okayama suffered terrible damage in the war, losing more than 12,000 households.
During Japan's economic boom of the 1960s, Okayama developed rapidly as one of the most important cities in the Chūgoku and Shikoku regions. In 1972, the Sanyō Shinkansen began service between Shin-Ōsaka and Okayama stations. Two years later, Shinkansen service was extended to Hakata.
In 1988, the Seto-Ōhashi Bridge was opened, and connected Okayama with Shikoku directly by rail and road.
The city became a core city in 1996 and a designated city on April 1, 2009.
The city of Okayama is located in the southern part of Okayama Prefecture, which in turn is located in western part of the island of Honshū. The city is bounded on the south by the Inland Sea. Asahi River crosses Okayama.
Since Okayama became a designated city in 2009, the city has been divided into four wards (ku).
Kojima, Mitsu, and Akaiwa Districts have all since been dissolved as a result of these mergers.
Okayama has a mild climate in comparison to most of Japan. The city is ranked as the second driest and the fourth sunniest city in the Chūgoku region. The climate is classified under the Köppen climate classification as humid subtropical (Cfa).
The local climate is warm enough throughout the year to support olive trees. Okayama is often called "The Sunny Country" because of its low rainfall.
The city is located in the Okayama Plain, where rice, eggplant, and white Chinese chives are notable products. White peaches and grapes are cultivated in the mountainous, northern part of the city.
In 2005, the city's gross domestic product was 800 billion yen, nearly 10% of the GDP of Okayama Prefecture. Greater Okayama, Okayama Metropolitan Employment Area, has a GDP of US$63.1 billion as of 2010. The main industries are machine tools, chemicals, foodstuffs and printing. Kōnan, a district in the southern part of the city, is the most developed industrial zone.
Okayama is the core of the Okayama metropolitan area, which includes the cities of Kurashiki and Sōja. The main commercial district is Omotechō, near Okayama Castle and Kōraku-en, and the area surrounding Okayama Station. Omotechō has many covered shopping arcades.
The headquarters of Aeon Corporation, a private English language school with more than 3,000 employees, is located in Okayama.
Okayama Castle and Kōraku-en are Okayama's most notable attractions.
Okayama Castle (nicknamed Ujō (烏城), meaning "crow castle") was constructed in 1597 by Ukita Naoie, a Japanese feudal lord. It was destroyed by bombing in 1945 during World War II but reconstructed in 1966.
Kōraku-en, known as one of the three best traditional gardens in Japan, lies south of the castle grounds. Kōrakuen was constructed by Ikeda Tsunamasa over 14 years, and completed in 1700.
Sōgen-ji, a large Buddhist monastery belonging to the Rinzai sect, is located near the center of the city. Several of the abbots of major monasteries in Kyoto are from Sōgen-ji.
Every August since 1994 Okayama has seen the Momotarō Matsuri (Festival), which is an amalgam of three different festivals, including the ""Uraja"" (ogre) festival, which is a kind of Yosakoi dance.
Okayama has a professional symphony orchestra, the Okayama Symphony Orchestra, which performs at the Okayama Symphony Hall.
There are many museums in the city, including the Okayama Prefectural Museum, the Okayama Prefectural Museum of Art, the Hayashibara Museum of Art, the Okayama Orient Museum, the Yumeji Art Museum, and the Okayama Digital Museum.
Okayama has several traditional dishes. Barazushi (ばらずし), a dish made with sushi rice, contains fresh fish from the Seto Inland Sea. Kibi dango (Okayama) (吉備団子) gel-like balls made from a powder of millet and rice, are well known sweets from the area.
The Sanyo Shimbun is the local newspaper serving the greater Okayama area. There are six television stations serving the Okayama area and part of Kagawa Prefecture. Three FM and three AM radio stations also serve the region.
Okayama has many sports teams. In recent years, volleyball team Okayama Seagulls and football club Fagiano Okayama have been established. In 2009, Fagiano Okayama FC gained promotion to the J. League, the highest football league in Japan.
Okayama was the birthplace of the 31st Yokozuna, Tsunenohana Kan'ichi, in 1896. He won 10 championships, 8 during his time as a Yokozuna.
Okayama University, founded as a medical school in 1870 and established in 1949 as a national university, is in the city. Today, Okayama University is one of Okayama's largest universities, with 11 faculties and six graduate schools.
There are seven private universities, three junior colleges, 24 high schools (16 public, eight private), seven combined junior high/high schools (two public, five private), 37 junior high schools (36 municipal, one national) and 93 elementary schools (91 municipal, two private) in the city.
JR West's Okayama Station is a major interchange, with trains from Shikoku, Sanin and Sanyo connecting to the Sanyo Shinkansen. Local rail lines serving Okayama Station include: Sanyo Main Line, Hakubi Line, Akō Line, Uno Line, Seto-Ōhashi Line, Tsuyama Line, and Kibi Line.
Okayama has kept an operational tram system since the Meiji period. It is managed by Okayama Electric Tramway and offers two lines: the Higashiyama Main Line and the Seikibashi Line.
Seven bus companies provide service within the city limits: Bihoku Bus (備北バス), Chūtetsu Bus (中鉄バス), Okaden Bus (岡電バス), Ryōbi Bus (両備バス), Shimoden Bus (下電バス), Tōbi Bus (東備バス), and Uno Bus (宇野バス).
Okayama Airport, located in the northern part of the city, provides domestic service to Tokyo-Haneda, Sapporo-Chitose, Okinawa-Naha, and Kagoshima. International air service is provided to Seoul-Incheon, Guam, Beijing, Hong Kong, Shanghai-Pudong, and Dalian.
Okayama has 6 sister cities around the world.