Ouigo (French pronunciation: [wiˈɡo]) is a French low-cost service range of both conventional and high-speed trains. The literal translation of Ouigo from French to English is "yes go"; the name is also a play on words with the English homonym "we go." It is composed of two different services: Ouigo Grande Vitesse, which is a brand of SNCF operating high-speed trains; and Ouigo Vitesse Classique, a brand under which Oslo, a subsidiary of SNCF, operates conventional speed trains.
Ouigo was established in 2013 to offer budget long-distance services on the core routes of the French railway network. The first train ran on 2 April 2013. Ouigo rolling stock was configured in a 'no-frills' arrangement, with minimal onboard amenities and a single class of seating. It was intended that passengers seeking a higher-level service would continue to use SNCF's regular high-speed trains since rebranded as TGV inOui. Ouigo quickly proved popular with the travelling public, selling in excess of 2.5 million tickets during its first year of operation, and was rapidly expanded to cover more stations and regions.
On 10 December 2017, Ouigo launched a new timetable and began to serve the central Paris termini for the first time. SNCF stated in the late 2010s that they sought for around 25 percent of the travelling public to use the Ouigo service. Originally, Ouigo operated only TGV high-speed train sets, but on 11 April 2022, the Ouigo Vitesse Classique service launched, using older locomotive-hauled rolling stock on conventional lines. This offered slower service, but with even cheaper tickets available. The high-speed service was therefore rebranded as Ouigo Grande Vitesse.
During the early 2020s, SNCF decided to expand Ouigo internationally for the first time, establishing the sister company Ouigo España to offer a similar service in neighbouring Spain.