In London, official taxis are almost universally referred to as "Black Cabs". While modern versions are now primarily electric (the LEVC TX model) and can occasionally be found in different colors for advertising purposes, the name "Black Cab" persists due to their iconic historical appearance. These are the only vehicles authorized to be hailed on the street or picked up at a taxi rank. To become a Black Cab driver, individuals must pass an incredibly difficult exam known as "The Knowledge," which requires memorizing 25,000 streets and thousands of landmarks within a six-mile radius of Charing Cross. Besides Black Cabs, London also has "Minicabs" (Private Hire Vehicles). Unlike Black Cabs, Minicabs cannot be hailed on the street and must be pre-booked via a phone call or an app like Uber, Bolt, or Addison Lee. While a Black Cab uses a meter to determine the fare, Minicabs usually provide a fixed price at the time of booking. To Londoners, "taking a cab" usually implies a Black Cab, while "booking a car" often refers to a minicab.