It’s not you. Some of your favorite websites really do look different today.

July 12 has been deemed a “day of action” by more than 200 websites, companies and organizations in support of net neutrality, a fundamental rule underpinning the internet that prevents service providers from playing favorites with or otherwise discriminating against data as it travels on their network.

The list of participants includes tech giants such as Google, Amazon, Twitter, Facebook and Netflix, and literally hundreds of other sites, from Reddit, Spotify and Airbnb to Pornhub, each of which is raising the issue Wednesday with their own spin.

Mark Zuckerberg also threw his hat in the ring, personally pledging Facebook’s continued backing of pro-net neutrality Federal Communications Commission regulations.

Video platform Vimeo told Recode it will prominently feature a brief video explaining the importance of net neutrality, which both President Donald Trump and Ajit Pai, the Republican FCC chairman he appointed, oppose.

This spring, Pai took the first steps toward dismantling a 2015 Obama-era net neutrality rule that classified telecoms as Title II “common carriers,” which, among other things, prevents internet service providers (ISPs) from making “unjust or unreasonable discrimination in charges, practices, classifications, regulations, facilities, or services.”

Pai argues the rule has stifled internet investment and innovation, but most major internet players disagree, painting it instead as a play by companies like Comcast and Verizon to tip the scales in their favor at the cost of... well, everyone else.

Without net neutrality, for instance, Comcast could hypothetically prioritize content produced by NBC, which it owns, while slowing access to Netflix. Similarly, Verizon, which owns HuffPost’s parent company, Oath, could allot extra bandwidth to HuffPost content at the expense of others.

Comcast went on a PR offensive ahead of Wednesday’s action, trumpeting its support for an “open internet,” while somehow also trying to make the case that Title II protections and net neutrality are unrelated.

Verizon, which has sued the FCC over the rules, also affirmed its commitment to an “open internet” on Wednesday, but countered that regulating internet providers as common carriers hinders their ability to innovate.

“It’s in all of our interests to ensure that consumers can access the legal content of their choice when and how they want,” wrote Will Johnson, senior vice president for federal regulatory and legal affairs. “It also is in all of our interests for businesses to have certainty so they can invest in networks and create new products and offers with confidence. And providers throughout the Internet ecosystem should be able to expand and grow their networks and services without fear of being cut-short by regulation.”

(HuffPost’s union is represented by the Writers Guild of America, East, which has joined Wednesday’s action in support of net neutrality.)

AT&T, meanwhile, attempted to play both sides of the coin by simultaneously endorsing the “day of action” while also continuing to support scrapping Title II. Critics accused the telecommunications giant of “co-opting” the movement:

you are not "joining" the net neutrality day of action if you fundamentally disagree with the cause. that's not joining, that's coopting. — Tony Romm (@TonyRomm) July 11, 2017

Mignon Clyburn, the FCC’s lone remaining commissioner who is also a Democrat, broke with Pai Wednesday and re-upped her commitment to net neutrality. In an unambiguous statement, she positioned Pai’s efforts to repeal Title II as being on the wrong side of history.

“Today I stand with those who believe that a free and open internet is a foundational principle of our democracy,” she said. ”That is why I am excited that on this day consumers, entrepreneurs and companies of all sizes, including broadband providers and internet startups, are speaking out with a unified voice in favor of strong net neutrality rules grounded in Title II.”

As the internet nonprofit Mozilla explains it:

Net neutrality is fundamental to free speech. Without net neutrality, big companies could censor people and perspectives online. Net neutrality has been called the “First Amendment of the Internet.” Net neutrality protects small businesses and innovators who are just getting started. Without net neutrality, creators and entrepreneurs could struggle to reach new users. Investment in new ideas would dry up and only the big companies would survive, stifling innovation. Net neutrality allows consumers — not big companies — to choose what they watch & do online. Without net neutrality, ISPs could decide you watched too many videos on Netflix in one day and throttle your Internet speeds, while keeping their own video apps running smooth.

“The FCC wants to destroy net neutrality and give big cable companies control over what we see and do online,” said Battle for the Net, a consortium of advocacy groups, in an announcement explaining the need for Wednesday’s action. “If they get their way, they’ll allow widespread throttling, blocking, censorship, and extra fees. On July 12th, the Internet will come together to stop them.”

The Internet needs to remain a level playing field where the reach of one’s voice is determined by quality of ideas and not a handful of CEOs. Tom Perez, chairman of the Democratic National Committee

In a statement Wednesday, Democratic National Committee Chairman Tom Perez also voiced his support for net neutrality and encouraged followers to call their representatives and write the FCC.

“The Internet needs to remain a level playing field where the reach of one’s voice is determined by quality of ideas and not a handful of CEOs,” he said. “The free flow of information shouldn’t be impeded by greedy gatekeepers. The Republicans who put the wallets of big telecom companies and their lobbyists over the best interests of their constituents need to be held accountable.”

The FCC is accepting public comment on its proposed rollback until July 17.

This article has been updated with more comments on net neutrality.