Rijeka is the principal seaport and the third-largest city in Croatia (after Zagreb and Split). It is located in Primorje-Gorski Kotar County on Kvarner Bay, an inlet of the Adriatic Sea and in 2011 had a population of 128,624 inhabitants. Historically, because of its strategic position and its excellent deep-water port, the city was fiercely contested, especially among Italy, Hungary (serving as the Kingdom of Hungary's largest and most important port), and Croatia, changing hands and demographics many times over centuries. According to the 2011 census data, the majority of its citizens are Croats, along with a large minority of Serbs, and smaller numbers of Bosniaks and Italians.

Rijeka is the main city and county seat of the Primorje-Gorski Kotar County. The city's economy largely depends on shipbuilding (shipyards "3. Maj" and "Viktor Lenac Shipyard") and maritime transport. Rijeka hosts the Croatian National Theatre Ivan pl. Zajc, first built in 1765, as well as the University of Rijeka, founded in 1973 but with roots dating back to 1632 School of Theology.

Apart from Croatian and Italian, linguistically the city is home to its own unique dialect of the Venetian language, Fiuman, with an estimated 20,000 speakers among the autochthonous Italians, Croats and other minorities. Historically Fiuman served as the main lingua franca between the many ethnicities inhabiting the multi-ethnic port town. In certain suburbs of the modern extended municipality the autochthonous population still speaks Chakavian, a dialect of the Croatian language.

In 2016, Rijeka was selected as the European Capital of Culture for 2020, alongside Galway, Ireland.