天津市，简称津，是中华人民共和国直辖市、国家中心城市和中国北方最大沿海开放城市。天津位于华北平原的海河各支流交汇处，东临渤海，北依燕山；有海河在城中蜿蜒而过，跨越海河的各式桥梁形成“一桥一景”的景致。
天津因漕运而兴起，1404年12月23日正式筑城。自1860年天津开放为通商口岸后，英法等九国在天津设立租界，清廷洋务派亦在天津兴办实业，使天津成为中国北方对外开放的前沿和近代中国洋务运动的基地。在领风气之先的同时，天津近代工业、商业、金融业等发展迅速。由天津开始的军事、教育、司法、交通、通讯、工业等方面的近代化建设，均开中国之先河。天津成为当时中国第二大的工商业城市和北方最大的金融商贸中心。
2006年3月，国务院批复的《天津市总体规划》将天津完整定位为“国际港口城市、北方经济中心、生态城市”，并将“推进天津滨海新区开发开放”纳入国家发展战略，设立为国家综合配套改革试验区。2007年11月，中国、新加坡两国政府选址天津共同建设中新生态城。2015年4月，中国（天津）自由贸易试验区挂牌成立，成为中国北方第一个自由贸易试验区。经过自1990年代开始的工业东移战略，天津市已经初步形成了“中心城区-滨海新区”和“天津港-天津南港”的双城双港的城市格局。2015年4月，《京津冀协同发展纲要》确定天津市为“全国先进制造研发基地、北方国际航运核心区、金融创新运营示范区和改革先行示范区”。
天津市举办了2013年的第六届东亚运动会和2017年第十三届全运会，同时是夏季达沃斯论坛和世界智能大会的常驻举办城市。此外，天津将是2023年亚足联亚洲杯的主办城市之一。

Tianjin alternately romanized as Tientsin, is a municipality and a coastal metropolis in Northern China on the shore of the Bohai Sea. It is one of the nine national central cities in Mainland China, with a total population estimated at 15,621,200 in 2016. Its built-up (or metro) area, made up of 12 central districts (all but Baodi, Jizhou, Jinghai and Ninghe), was home to 12,491,300 inhabitants in 2016 and is also the world's 29th-largest agglomeration (between Chengdu and Rio de Janeiro) and 11th-most populous city proper.
It is governed as one of the four municipalities under the direct administration of Chinese central government and is thus under direct administration of the State Council. Tianjin borders Hebei Province and Beijing Municipality, bounded to the east by the Bohai Gulf portion of the Yellow Sea. Part of the Bohai Economic Rim, it is the largest coastal city in Northern China and part of the Jing-Jin-Ji megapolis.
In terms of urban population, Tianjin is the fourth largest in China, after Shanghai, Beijing, and Guangzhou. In terms of administrative area population, Tianjin ranks fifth in Mainland China. The walled city of Tianjin was built in 1404. As a treaty port since 1860, Tianjin has been a major seaport and gateway to Beijing. During the Boxer Rebellion the city was the seat of the Tianjin Provisional Government. Under the Qing dynasty and the Republic of China, Tianjin became one of the largest cities in the region. At that time, numerous European-style buildings and mansions were constructed in concessions, many of which are well-preserved today. After the founding of the People's Republic of China, Tianjin suffered a depression due to the policy of the central government and 1976 Tangshan earthquake, but recovered from 1990s. Nowadays Tianjin is a dual-core city, with its main urban area (including the old city) located along the Hai River, which connects to the Yellow and Yangtze Rivers via the Grand Canal; and Binhai, an adjacent New Area urban core located east of the old city, on the coast of the Bohai Gulf. As of the end of 2010, around 285 Fortune 500 companies have set up base in Binhai. Since 2010, Tianjin's Yujiapu Financial District has become known as China's Manhattan and the city is considered one of the world's top 100 cities, including in the Global Financial Centres Index.Tianjin is ranked as a Beta (global second-tier) city by the Globalization and World Cities Research Network.
Tianjin is one of the top 25 cities in the world by scientific research outputs as tracked by the Nature Index, and home to multiple notable institutes of higher education in Northern China, including Tianjin University, Nankai University, Tianjin University of Technology, Tianjin Medical University, Tianjin Polytechnic University, Tianjin University of Science & Technology, Hebei University of Technology and Tianjin Normal University.