Illegal taxicabs, sometimes known as gypsy cabs, are taxicabs and other for-hire vehicles that are not duly licensed or permitted by the jurisdiction in which they operate. Most major cities worldwide require taxicabs to be licensed, safety-inspected, insured as for-hire vehicles and use taxi meters and there may also be requirements that the taxi driver be registered or accredited. However, many unlicensed cabs are in operation. Illegal cabs may be marked taxi vehicles (sometimes referred to as "speedy cabs"), and others are personal vehicles used by an individual to offer unauthorized taxi-like services. Illegal cabs are prevalent in cities with medallion systems, which restrict the number of legal cabs in operation. Since their introduction in 2009, Uber taxis, which are crowd-sourced smartphone-enabled unlicensed taxis, have been classified as illegal taxicabs in some jurisdictions.
A variety of terms are used in the industry to describe legal and illegal transportation providers. Hacks or Hackers is a common term that originated with the hackney horse, a breed of horse typically offered for hire in the 19th century. Other terms used are livery cab, car service, or jitney cab.
The phrases vary by locality and often refer to different classes of licensed transportation providers. For example, in Philadelphia a cab driver's license is called a hacker's license, while in New York City, livery cabs are licensed for telephone dispatch only.
In mainland China, illegal cabs are referred to as "black taxies" or "black cars" (黑车)
In Lagos, Nigeria, illegal cabs are usually referred to as "Kabu kabu".
In Hong Kong, illegal cabs are usually referred to as white card due to different plate appearance between commercial and non-commercial vehicles.
In Malaysia, illegal taxicabs are called prebet sapu (sweep privates).
In Mexico, illegal taxicabs are called taxi pirata (pirate taxi)
In Norway and Denmark, an illegal cab is called pirattaxi, "pirate taxi".