Paris is the centre of a national, and with air travel, international, complex transport system. The modern system has been superimposed on a complex map of streets and wide boulevards that were set in their current routes in the 19th century. On a national level, it is the centre of a web of road and railway, and at a more local level, it is covered with a dense mesh of bus, tram and metro service networks.

Sustainable transport refers to ways of transportation that are sustainable in terms of their social and environmental impacts. Components for evaluating sustainability include the particular vehicles used for road, water or air transport; the source of energy; and the infrastructure used to accommodate the transport. Transport operations and logistics as well as transit-oriented development are also involved in evaluation. Transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental and climate impacts of the system. Transport systems have significant impacts on the environment, accounting for between 20% and 25% of world energy consumption and carbon dioxide emissions. The majority of the emissions, almost 97%, came from direct burning of fossil fuels. In 2019, about 95% of the fuel came from fossil sources. The main source of greenhouse gas emissions in the European Union is transportation. In 2019 it contributes to about 31% of global emissions and 24% of emissions in the EU. In addition, up to the COVID-19 pandemic, emissions have only increased in this one sector. Greenhouse gas emissions from transport are increasing at a faster rate than any other energy using sector. Road transport is also a major contributor to local air pollution and smog.