American cab firm Uber promises lower prices and quicker pick-ups. But will its high-tech approach succeed?
The American firm arrived in the UK in 2012 with the aim of shaking up the taxi and minicab market.
Uber, which was set up in San Francisco in 2009, describes itself as a "ridesharing service".
It uses a software app to match customers with Uber-approved drivers in their area, and claims to be both cheaper and quicker than traditional taxis.
Uber launched in London in 2012, and has been establishing itself in other UK cities ever since, including Birmingham, Manchester, Newcastle and Edinburgh.
But the service has seen considerable opposition around the world from taxi drivers and companies, as well as some politicians and regulators.
How does Uber work?
If you want to use Uber’s service and you’re in a city where it has been introduced, the first step is to download its smartphone app.
When you request a taxi, the app uses your phone’s GPS to work out where you are and share your request with drivers nearby.
Once a driver has accepted your request, you’ll be told who the driver is and how soon you can be picked up.
The app also tells you roughly how much the journey will cost, although this can vary depending on traffic conditions.
Payment is made online through a registered debit or credit card and you don’t have to tip.
Who are Uber’s drivers?
The idea is that anyone can apply to drive for Uber: they're allowed to take customers once they've passed a vetting process and completed a training course.
At present in the UK, however, only people who are already registered private hire drivers can work for the company.
Registering usually involves paying a fee, undergoing criminal record checks and, in London for example, completing "the Knowledge" to prove you have a good grasp of the local road network.
Uber takes a 20-30% cut of its drivers’ earnings, but drivers must provide their own vehicles and are responsible for the cost of maintenance and fuel, for example.
Why has Uber proved controversial?
In the UK, Uber has faced the most resistance from black cab drivers in London.
In June 2014, cabbies in the capital protested against the decision by Transport for London to allow Uber to operate in the city by blocking traffic on major routes.
The drivers said that Uber was subject to less stringent regulations than they were.
Uber has also been accused of underhand tactics against competitors in the US, with some Uber employees alleged to have booked and then immediately cancelled rides with rivals.
The firm denies these claims.
An executive was reported to have threatened to "dig up dirt" on an American journalist who had been critical of the firm.
What are the alternatives?
A number of apps have been launched over recent years to make it easier to book traditional taxis and minicabs.
Hailo is an app that makes it easier for users hail black cabs: as well as London, it is now available in Leeds, Liverpool and Manchester.