On the Google Display network , your ad is eligible to show on a webpage if you:

On the Google Display network , your ad is eligible to show on a webpage if you:

  • Keywords match that webpage’s content
  • Landing page matches that web page’s content
  • Website matches that web page’s content
  • Ad text matches that webpage’s content

Answer : Keywords match that webpage’s content

Source: https://support.google.com/adwords/answer/2453986?hl=en