The Federal Communications Commission has voted on party lines to undo sweeping Obama-era “net neutrality” rules that guaranteed equal access to the internet.

The agency’s Democratic commissioners dissented in the 3-2 vote Thursday.

The FCC’s new rules could usher in big changes in how Americans use the internet. The agency got rid of rules that barred companies like Comcast, AT&T and Verizon from playing favorites with internet apps and sites.

The broadband industry promises that the internet experience isn’t going to change. But protests have erupted online and in the streets as everyday Americans worry that cable and phone companies will be able to control what they see and do online.

Net-neutrality supporters plan legal challenges. Some Democrats hope to ride that wave of public opinion into the 2018 elections.

Here’s a look at what the developments mean for consumers and companies.

WHAT IS NET NEUTRALITY?

Net neutrality is the principle that internet providers treat all web traffic equally, and it’s pretty much how the internet has worked since its creation. But regulators, consumer advocates and internet companies were concerned about what broadband companies could do with their power as the pathway to the internet — blocking or slowing down apps that rival their own services, for example.

___

WHAT DID THE GOVERNMENT DO ABOUT IT?

The FCC in 2015 approved rules, on a party-line vote, that made sure cable and phone companies don’t manipulate traffic. With them in place, a provider such as Comcast can’t charge Netflix for a faster path to its customers, or block it or slow it down.

The net neutrality rules gave the FCC power to go after companies for business practices that weren’t explicitly banned as well. For example, the Obama FCC said that “zero rating” practices by AT&T violated net neutrality. The telecom giant exempted its own video app from cellphone data caps, which would save some consumers money, and said video rivals could pay for the same treatment. Under current chairman Ajit Pai, the FCC spiked the effort to go after AT&T, even before it began rolling out a plan to undo the net neutrality rules entirely.

A federal appeals court upheld the rules in 2016 after broadband providers sued.

___

WHAT TELCOS WANT

Big telecom companies hate the stricter regulation that comes with the net neutrality rules and have fought them fiercely in court. They say the regulations can undermine investment in broadband and introduced uncertainty about what were acceptable business practices. There were concerns about potential price regulation, even though the FCC had said it won’t set prices for consumer internet service.

__

WHAT SILICON VALLEY WANTS

Internet companies such as Google have strongly backed net neutrality, but many tech firms have been more muted in their activism this year. Netflix, which had been vocal in support of the rules in 2015, said in January that weaker net neutrality wouldn’t hurt it because it’s now too popular with users for broadband providers to interfere.

__

WHAT HAPPENS NEXT

In the long run, net-neutrality advocates say undoing these rules makes it harder for the government to crack down on internet providers who act against consumer interests and will harm innovation. Those who criticize the rules say undoing them is good for investment in broadband networks.

But advocates aren’t sitting still. Some groups plan lawsuits to challenge the FCC’s move, and Democrats — energized by public protests in support of net neutrality — think it might be a winning political issue for them in 2018 congressional elections.