Facebook, Twitter, Google and dozens of other major technology companies have protested online against proposed changes to US net neutrality rules.
In support of the "Internet-Wide Day of Action to Save Net Neutrality" on Wednesday, more than 80,000 websites displayed banners, alerts, ads and short videos to urge the public to oppose the overturn of the landmark 2015 net neutrality rules.
The companies ranged from big social media platforms such as Facebook to streaming services such as Netflix and matchmaking website OkCupid.
Net neutrality is a broad principle that prohibits broadband providers from giving or selling access to speedy internet, essentially a "fast lane", to certain internet services over others.
The rule was implemented by the Obama administration in 2015.
Changes to the rule are being proposed by the head of the US Federal Communications Commision, Ajit Pai, who was appointed by President Donald Trump in January.
Pai wants the commission to repeal the rules that reclassified internet service providers as if they were utilities, saying the open internet rules harm jobs and investment.
At a Capitol Hill news conference, Democrats and internet companies vowed to fight the changes and suggested internet companies could slow internet speeds.
Senator Edward Markey said the internet "is under attack".
Facebook chief executive Mark Zuckerberg wrote on the social media platform: "Right now, the FCC has rules in place to make sure the internet continues to be an open platform for everyone. At Facebook, we strongly support those rules."
Twitter expressed support for the existing rules, encouraging users to protest while promoting the hashtag #NetNeutrality.
Online forum Reddit displayed a pop-up message that slowly loads text saying: "The internet's less fun when your favourite sites load slowly, isn't it?"
The US public has until mid-August to send comments to the FCC before the final vote.
