Video report by ITV News Consumer Editor Chris Choi
Expedia and trivago are among six online hotel booking sites that will make changes to end misleading sales tactics and hidden charges after a probe by the competition watchdog.
Booking.com, Agoda, Hotels.com and ebookers were also investigated by the Competition and Markets Authority (CMA) after it raised "serious concerns" over tactics used in the sector.
The CMA said the sites have voluntarily committed to the measures, including:
Changes to make search results clearer
Ending pressure selling
Making discount claims more transparent
Displaying all compulsory charges.
The CMA said it will "do whatever it can" to bring the rest of the online hotel booking sector up to the same standard.
Andrew Tyrie, chairman of the CMA, said: "The CMA has taken enforcement action to bring to an end misleading sales tactics, hidden charges and other practices in the online hotel booking market. These have been wholly unacceptable."
The CMA stressed not all of the six sites were guilty of using the tactics, but have still committed to the changes.
They must make the changes by September 1 and the CMA warned it will take further enforcement action if it finds evidence of others breaking the law.
The watchdog will write to hotel booking sites across the sector - including travel agents, search engines and hotel chains - to explain how they must comply with consumer protection law.
What can you do to avoid getting stung between now and September?
The consumer group Which? have shared their top five tips for using hotel booking sites:
Don’t be fooled - compare prices with other holiday companies and travel agents to check savings are genuine, even when using price-comparison tools as no single site has the best deal every time.
Before you reach for your credit card, why not see if you can cut out the middleman altogether? Booking sites typically take around 15% commission, so it’s savvy to call the hotel and ask if it can do better.
Sometimes ‘free cancellation’ really is free, or very cheap (less than £10) - in which case, it may be worth opting for this over the non-refundable rate.
Hotels will often slash their prices if they have empty rooms at the last minute so you can cancel and rebook if the price drops.
Don't trust pressure selling tactics - tight deadlines and promises of a discount are designed to make you feel rushed, but you always have time to shop around.