TripAdvisor, Inc., is an American travel and restaurant website company providing hotel and restaurant reviews, accommodation bookings and other travel-related content. It also includes interactive travel forums.

TripAdvisor was an early adopter of user-generated content. The website services are free to users, who provide most of the content, and the website is supported by a hotel booking facility and an advertising business model.

TripAdvisor, headquartered in Needham, Massachusetts, is the largest travel site in the world, with more than 315 million members and over 500 million reviews and opinions of hotels, restaurants, attractions and other travel-related businesses. TripAdvisor Media Group operates 25 travel brands including TripAdvisor, Airfarewatchdog, BookingBuddy, Citymaps, Cruise Critic, Family Vacation Critic, FlipKey, GateGuru, Holiday Lettings, Holiday Watchdog, Independent Traveler, Jetsetter, lafourchette, Niumba, OneTime, SeatGuru, SmarterTravel, Tingo, TravelPod, Tripbod, VacationHomeRentals, Viator, and VirtualTourist. TripAdvisor operates websites internationally, in such places as Austria, Australia, Brazil, Canada, China (under the brand 猫途鹰 www.tripadvisor.cn), Denmark, France, Germany, Greece, India, Indonesia, Ireland, Italy, Japan, Mexico, The Netherlands, Norway, Poland, Portugal, Russia, Serbia, Singapore, Spain, Sweden, Thailand, Turkey, the U.K., and the U.S.

In February 2000, TripAdvisor was founded by Stephen Kaufer, Langley Steinert, and several others. Kaufer says the original idea wasn't a user generated social media site to swap reviews. Rather, "We started as a site where we were focused more on those official words from guidebooks or newspapers or magazines. We also had a button in the very beginning that said, "Visitors add your own review", and boy, did that just take off. Pretty soon the number of average consumer reviews far surpassed the number of 'professional reviews'. That is when the site really turned into this collection of what the normal traveler was saying wherever they were going." Original financing was obtained from Flagship Ventures, the Bollard Group, and private investors.

In 2004, the company was purchased by IAC/InterActiveCorp.

In August 2005, IAC spun off its travel group of businesses under the Expedia, Inc. name.

In April 2009, TripAdvisor launched its official site in China, www.daodao.com. Since then it has indexed more than 20,000 hotels and restaurants information and customer reviews, and made top lists, becoming one of the biggest travel websites as of July 2011.

In September 2010, SmarterTravel, part of TripAdvisor Media Group, launched SniqueAway (now Jetsetter), the first members-only site where each travel deal is endorsed by the people.

In March 2011, TripAdvisor informed all registered TripAdvisor members that an unauthorized third party had stolen some of TripAdvisor's email list and might use it to create spam messages. No passwords or other information was stolen. This happened shortly before many other companies reported similar thefts of the addresses on their email lists.

In April 2011, it was announced that Expedia would split into two publicly traded companies by spinning off the TripAdvisor brand of travel sites. According to Expedia CEO Dara Khosrowshahi, the move "allows the two businesses to be pure plays and to operate with the proper amount of focus to grow respectively."

According to a July 2011 PhoCusWright survey of 3,641 respondents, solicited at random through a pop-up invitation link on TripAdvisor.com and commissioned by Trip Advisor, “98% of participants found that TripAdvisor’s hotel reviews … accurately reflect the experience.”

In December 2011, TripAdvisor was spun off from Expedia in a public offering.

TripAdvisor states it is the world’s largest travel site, with nearly 280 million unique monthly visitors.

In April 2012, the company launched a connection to Facebook that lets users select reviews from people in their social graph.

In August 2014, a survey found that TripAdvisor was the most widely recognized, used, and trusted travel website.

In October 2014, Trip Advisor released a new feature, "Just for you", offering tailored hotel recommendations based on the user's preferences and search history on the site. This feature mirrored the "Tribes" feature launched on competitor site Gogobot in 2013.

In 2015, Tripadvisor started letting users not only rate places but tag them, saying, for example that a place offers brunch, is open on Sunday, or offers delivery, takeout, etc.

In May 2007 TripAdvisor acquired Smarter Travel Media operator of SmarterTravel.com and BookingBuddy.com; SeatGuru.com; TravelPod.com; and Travel-Library.com. Also in May 2007, TripAdvisor acquired The Independent Traveler, Inc., publisher of Cruise Critic.com and IndependentTraveler.com

In February 2008, TripAdvisor acquired Holiday Watchdog, a user-generated travel site in the U.K. In July 2008, TripAdvisor acquired Virtualtourist, a travel website with reportedly over 1 million registered members and OneTime.com, a travel comparison site.

In July 2008, TripAdvisor acquired a majority stake in FlipKey.com, a vacation-rental website. In October 2009, TripAdvisor purchased Kuxun.cn, China’s second-largest consumer travel site and hotel and flight search engine. Kuxun was later sold to Meituan.

In June 2010, TripAdvisor acquired the United Kingdom's largest independent vacation rental website, holidaylettings.co.uk.

In July 2011, TripAdvisor announced its acquisition of Where I've Been, a Chicago-based Travel Facebook app for an undisclosed sum.

In October 2012, TripAdvisor announced its acquisition of Wanderfly, an NYC-based travel inspiration website for an undisclosed sum.

In April 2013, TripAdvisor announced its acquisition of Jetsetter, an NYC flash sale site.

In June 2013, TripAdvisor announced its acquisition of GateGuru, an NYC-based flight and airport information mobile app for an undisclosed sum.

In October 2013, TripAdvisor announced its acquisition of Oyster.com, an NYC-based hotel review and photography website, for an undisclosed sum.

In May 2014 TripAdvisor acquired Vacation Home Rentals and Tripod.

In July 2014, TripAdvisor announced its acquisition of La Fourchette (thefork.com) for $140M

In August 2014, TripAdvisor acquired Viator, Inc. for $200M.

In October 2014, TripAdvisor acquired mytable and restopolis.

In January 2015, TripAdvisor announced its acquisition of Iens, a Dutch restaurant review website and SeatMe, a Dutch website for reserving seats in a restaurant. According to TripAdvisor, this is to stimulate growth in The Netherlands.

In April 2015, TripAdvisor acquired Portuguese startup BestTables.

In May 2015, TripAdvisor acquired Australian startup Dimmi for $25 million. In October 2016, TripAdvisor announced its acquisition of Couverts, a Dutch restaurant review , a Dutch website for reserving seats in a restaurant. According to TripAdvisor, this is to stimulate growth in The Netherlands.

TripAdvisor has been the subject of controversy for allowing unsubstantiated anonymous reviews to be posted about any hotel, B&B, inn, or restaurant.

Approximately 30 hotels have been blacklisted by TripAdvisor for suspicious reviews, including a Cornwall hotel that bribed guests to leave positive reviews of the hotel.

TripAdvisor has stated that reviews are not posted to the website instantly, but are subject to a verification process which considers the IP address and email address of the author, and tries to detect any suspicious patterns or obscene or abusive language. The website also allows the community of users to report suspicious content, which is then assessed by a team of quality assurance specialists, and TripAdvisor alerts the owner or manager of a TripAdvisor-listed establishment whenever a review is posted on their listing.

In September 2011, the UK Advertising Standards Authority (ASA) launched a formal investigation into TripAdvisor after receiving a complaint submitted by online investigations company KwikChex that its claims to provide trustworthy and honest reviews from travelers are false. The ASA found that TripAdvisor "should not claim or imply that all its reviews were from real travellers, or were honest, real or trusted", and as a result of the investigation, TripAdvisor was ordered to remove the slogan "reviews you can trust" from its UK web site. It changed its hotel review section slogan to 'reviews from our community.'

TripAdvisor stated that the branding change had been planned for some time and that changes began in June 2011, before the ASA investigation. ASA commented that "it was concerned that consumers might be fooled by fraudulent posts since the entries could be made without any form of verification," but recognised that TripAdvisor used "advanced and highly effective fraud systems" in an attempt to identify and remove fake content.

In 2012, an action was brought in a Sheriff Court in Scotland, by a guesthouse owner who claimed damages for malicious statements. TripAdvisor asserted that the Scottish courts lacked jurisdiction. The outcome of this case was called a "landmark victory", as the pursuer (plaintiff) secured two points of law in the UK:

The case was found to involve issues relating to the Unfair Terms in Consumer Contracts Act, 1977: these issues were referred to a higher court in Stornoway.

In 2012, TripAdvisor was fined $80,000 by the U.S. Department of Transportation for violating new fair trading regulations requiring taxes and fees to be shown for prices quoted for airfares.

In May 2013 a fake restaurant was set up by a disgruntled businessman and reportedly had diners looking for the eatery in an alley filled with garbage cans. The fake listing went undetected on TripAdvisor for over 2 months until it was exposed by KwikChex.

In March 2014, TripAdvisor's Chinese site came under scrutiny because KwikChex uncovered that a reviewer had reviewed 51 Parisian restaurants in one month, while also reviewing 50 Hotels in other countries.

In December 2014, the Italian Antitrust Authority fined TripAdvisor €500,000 for improper commercial practices on the TripAdvisor website. The Italian Authority stated that Tripadvisor and its Italian arm should stop publishing misleading information about the sources of the reviews. In June 2015, a fake restaurant created by a newspaper rose to the top of the site's rankings in Italy.

An ex-hotel manager at Meriton says that guests were offered inducements to change ratings they left on the site.

Dietmar Doering, a German hotelier based in Sri Lanka accused TripAdvisor of hosting malicious reviews of his resort The Cosy Beach in Marawila. He claimed he was compelled to take legal action for the estimated damages of US$500,000.

In November 2017, TripAdvisor was cited in two reports from the Milwaukee Journal Sentinel and CBS News that it was responsible for deleting numerous reviews that raised red flags of complaisant criminal responsibility by resorts in Playa del Carmen, a popular tourist resort in the Yucatán Peninsula of Mexico. The reports cited that the company deleted reviews from two women who were raped at the Iberostar Paraiso Maya in separate incidents 2010 and 2015 respectively, one of which involved a hotel security guard. After assurances from hotel staff they would help out and contact the authorities but failed to take any follow-up action, the women took their advisories and warnings to TripAdvisor, which deleted their reviews. The first victim, Kristie Love, had her review eventually put back up on TripAdvisor's site successfully, while in the case of the second victim, Jamie Valeri, the company refused to budge after citing her report as "hearsay." The reports also highlighted at least a dozen other incidents at hotels and resorts across Mexico, including that of a 29-year-old man who was raped by a massage therapist at a resort in the same area, where reviewers had attempted to warn people through reviews on the company's site about criminal incidents that the resorts and local authorities had failed to pursue any criminal or legal action for, only to have those reviews either taken down or declined for posting by TripAdvisor.

TripAdvisor policies claim they are aimed to encourage travelers to post more reviews but could be unfriendly for small businesses that are not mainstream. If photos posted by travelers hurt the business like it is in case of exposition of arts or a museum, the business owner is not allowed to remove the photos if the photos comply with TripAdvisor policies. Nor do the owner have any chance for removing their business from TripAdvisor altogether if the owner becomes unhappy with the partnership.