Ads.txt is a text file stored in the main folder of a website that contains the list of companies authorized to sell the site's inventory. IAB Tech Lab released this standard in May 2017 in order to combat ad fraud by means of something able to "certify" the authenticity of advertising spaces.
Ads.txt solves this problem in a very simple way: it just lists all the platforms that are authorized to sell a publisher's inventory.
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