Pay-per-click (PPC)

Pay-per-click (PPC) is an online advertising model where advertisers pay a fee each time a user clicks on their ad. 

Publishers (search engines, social media platforms) employ an auction system to determine the placement of ads (ad rank). They consider the bid amount, ad quality, and relevance of the ad to the search query. PPC ads appear alongside or above organic search results, with a mark showing that they are paid advertisements. The ads with the highest combination of bid amount and ad quality hit the most prominent positions.  

Advertisers conduct keyword research to select those most relevant to their target audience. For example, an online travel agency (OTA) seeking to promote its vacation packages should define advertising goals, analyze its customers, and study competitors to brainstorm a list of keywords that users might type in when searching for services similar to theirs. The OTA pays a fee each time someone clicks on their ad, regardless of whether the user makes a purchase. 

In travel, metasearch engines (Tripadvisor, Skyscanner, Kayak, etc.) use the PPC model to generate revenue, with travel companies paying for clicks on their listings.