Internet Slowdown Day will be headlined by several major companies when Web users and so-called Net activists come together on Sept. 10 to demonstrate what the Internet might look like if so-called fast lanes are allowed as part of the new net neutrality rules that the Federal Communications Commission is currently considering.

Fight for the Future, the group behind the advocacy event, announced Thursday that several top websites — including Reddit, Foursquare, Vimeo, Wordpress, and Boing Boing — will take part in the online event.

Lest you be worried that your Internet service will get bogged down on Wednesday, fear not. Internet Slowdown Day is meant to be a symbolic protest.

Participating sites will display an “infinitely-loading site loading icon” to illustrate to visitors what the Web could be like if broadband providers are allowed to offer priority service as part of the upcoming net neutrality rules. The companies and activist organizations — including the American Civil Liberties Union, Electronic Frontier Foundation, and Greenpeace — will also call on visitors to contact their U.S. representatives and officially protest the “fast lane” aspect of the potential new regulation that had originally been proposed by FCC Chairman Tom Wheeler as part of the new net neutrality rules.

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Net neutrality has long been a subject of debate on the Internet. The principle is simple: Internet service providers — such as AT&T, Comcast, Time Warner Cable, and Verizon — and governments around the world should treat all Internet traffic the same. This means ISPs shouldn’t block or slow down traffic on their local broadband networks based on individual users. And they shouldn’t modify their services based on the type of traffic those users are accessing or by the type of service that’s sending the content.

The FCC has been redrafting rules to protect this principle, since earlier rules adopted in 2010 were thrown out by a federal court in January. While Net activists all agree that new rules are necessary, they were unhappy with one aspect of the FCC chairman’s original proposal. In that proposal leaked in April, the new rules would explicitly allow broadband providers to offer “paid prioritization” services to companies willing to pay for faster access to end users. These so-called fast lanes would act much like HOV lanes on a highway, allowing certain packets that are marked priority to travel in a less congested lane to their destination. This would allow some companies, such as the video service Netflix, to get its packets of streaming video through congested networks faster than other services, which haven’t paid for access to the fast lane.

Fight for the Future argues that the proposed rules would allow major broadband providers “to create a two-tiered Internet, with slow lanes (for most of us) and fast lanes (for wealthy corporations that are willing to pay fees in exchange for fast service).” The organization also argues that the rules would hand power to Internet service providers and allow them to “discriminate against online content and applications.”

Wheeler has backtracked with regard to his original proposal thanks in large part to strong public backlash. He says the FCC will not allow an Internet of “haves” and “have-nots” to be created. But the current proposal that is still open for public comment does ask if there are any acceptable instances where paid priority should be allowed.

So far, the matter hasn’t been decided. However, some of the most prominent online companies in the world, including Google and Facebook, have railed against this aspect of the proposed rules, and some industry pundits say that they would negatively affect competition on the Web.

CNET’s Marguerite Reardon contributed to this story.