Metro. Two driverless lines. The Red Line runs the length of Sheikh Zayed Road from the airport through Deira, Downtown and the Marina. The Green Line loops through the old city and serves the souks, Al Fahidi and Al Ghubaiba. They interchange at Union and BurJuman. The first carriage is Gold Class and the second is Women and Children only, both enforced.
Nol card. One card for metro, tram, bus and water bus. Buy a Silver Nol at any station, load credit, tap in and tap out.
Taxis. Metered, regulated and cheap. Cream with coloured roofs; pink roofs have women drivers, for women and families. Careem and Uber both operate.
Abras. Wooden boats across the Creek for one dirham, cash to the boatman. The best value in the city.
Tram. One line around the Marina and JBR, on the Nol card. The Palm Monorail is not on Nol and needs its own ticket.
Buses. Extensive, air-conditioned, with air-conditioned shelters. E100/E101 to Abu Dhabi, E16 to Hatta.
Walking. Realistic in the old city and on the built promenades, and not much else. Blocks are large, roads are wide, and from May to September any real distance outdoors is unwise. Jaywalking is fined.
For the detail, see Getting Around Dubai.