Today is a day of protest and calls for action from major players in the tech industry as the FCC prepares to roll back two-year-old protections for net neutrality. CEOs Mark Zuckerberg and Jack Dorsey and entire sites and apps like Reddit and Spotify are using the day to call on all users of the internet to write to the FCC and demand the protection of the open internet — and to oppose Republican FCC chairman Ajit Pai's vague plan to allow internet service providers like Comcast, AT&T, and Charter the ability to throttle the internet or block specific sites for users based on what they pay for.

"Without the guiding principles of Net Neutrality, it is entirely possible Twitter would not have come from a somewhat quirky experimental 140-character SMS service to where we are today," wrote Twitter's head of public policy Laura Culbertson in a blog post Tuesday night. Twitter also began promoting the hashtag #NetNeutrality at the top of its Trending column, marking, as Recode confirmed with them, the first time the company had promoted a hashtag supporting one of the company's public policy positions.

The occasion is that five days from now will be the first deadline for public comment on net neutrality rules, and Pai has said that while he opposed the 2015 guidelines approved under President Obama, he is open to hearing public opinion. Simultaneously today, physical, human protests are happening in Washington, DC.

Interestingly, AT&T even joined in the day of action, as The Verge reports, issuing a statement saying, "This may seem like an anomaly to many people who might question why AT&T is joining with those who have differing viewpoints on how to ensure an open and free internet. But that’s exactly the point — we all agree that an open internet is critical for ensuring freedom of expression and a free flow of ideas and commerce in the United States and around the world."

Writing in a Facebook post Wednesday morning, Zuckerberg says, "If we want everyone in the world to have access to all the opportunities that come with the internet, we need to keep the internet free and open."

Similarly, Google, Airbnb, Spotify, Amazon, College Humor, and others are pointing users to this site discussing the issue and actions to take — and Reddit has been particularly creative with splash pages like the one you can see in the gallery above, blocking users, April-Fools-like, to make a point about what the internet could look like under Pai's looser rules. (You may have also noticed the non-profit Mozilla's ads in support of net neutrality running on SFist recently.)

The New York Times reported in April that Pai has been far from clear on what his rollback plan would be, and he has said he would "seek public comment on how to preserve the basic principles of net neutrality — the prohibitions of blocking, throttling and paid priority for online traffic." That public opinion is what these companies are urging everyone to express in real fashion, and not just as a comment on Reddit, today.

Pai argues that the more regulations there are, the less companies will want to invest in improving broadband networks themselves — which is the argument that the companies and their lobbyists have been making as they cheer Pai on.

Also, apparently, chip makers and other Silicon Valley hardware makers tend to fall on the fewer-rules side of this debate too, as the NYT discussed.

But as Reddit co-founder (and soon-to-be Mr. Serena Williams) Alexis Ohanian (a.k.a. kn0thing on the site) writes,

When Steve [Huffman] and I started Reddit right out of college, we were just two kids with $12K in funding and some computers in Medford, MA. Our plan was to make something people wanted, because we knew if we accomplished that, we could win—even against massive incumbents.

But we wouldn’t have succeeded if users had to pay extra to visit our website, or if better-funded alternatives loaded faster. Our start-up got to live the American dream thanks to the open internet, and I want to be able to tell aspiring entrepreneurs with a straight face that they can build the next Reddit. If we lose net neutrality, I can’t tell them that.

It should be noted that Google did not opt to devote precious Doodle space to the issue today, or even run a banner on its uber-popular homepage.

Below, a statement from World Wide Web inventor Tim Berners-Lee.

Related: Video: Three Naked Women Explain Net Neutrality