Authenticity. To prevent somebody from modifying the page against your will, e.g. ISPs/Wifi hotspots inserting ads into all http pages. Example (out of many):

Authenticity. To prevent somebody from modifying the page against your will, e.g. ISPs/Wifi hotspots inserting ads into all http pages. Example (out of many): https://www.techdirt.com/articles/20140908/07191228453/comcast-using-packet-injection-to-push-its-own-ads-via-wifi-apparently-oblivious-to-security-concerns.shtml https://www.techdirt.com/articles/20140908/07191228453/comca...