The net neutrality rules are no longer the law of the land.

The repeal of Obama-era net neutrality protections officially took effect on Monday, nearly six months after the Republican-led Federal Communications Commission voted to roll back the rules.

In a press release Monday, the FCC said the repeal does away with "unnecessary, heavy-handed regulations" and replaces them with "common-sense regulations that will promote investment and broadband deployment."

While the move was supported by the telecom industry, it has faced fierce resistance from others. State officials, members of Congress, technology companies and various advocacy groups are still pushing to save the rules through legislation and litigation.

Here's what it means and what's really at stake.

What exactly is net neutrality?

The net neutrality rules were approved by the FCC in 2015 amid an outpouring of online support. The intention was to keep the internet open and fair.

Under the rules, internet service providers were required to treat all online content the same. They couldn't deliberately speed up or slow down traffic from specific websites or apps, nor could they put their own content at an advantage over rivals.

To take a classic example, this means Comcast (CCZ) couldn't just choose to slow down a service like Netflix (NFLX) to make its own streaming video service more competitive, nor could it try to squeeze Netflix to pay more money to be part of a so-called internet fast lane.

As Michael Cheah, general counsel at video site Vimeo, previously told CNNMoney: the point of the rules was "allowing consumers to pick the winners and losers and not [having] the cable companies make those decisions for them."

Why is net neutrality such a big deal?

If there's one thing that both sides can agree on, it's that the internet is increasingly central to our lives. Any change to how it's regulated is a hot button issue. (Remember the uproar over repealing internet privacy protections last year?)

"Everyone uses the internet and everyone uses these tech platforms," Michelle Connolly, a former FCC official who supports chairman Ajit Pai, previously told CNNMoney. "So issues that are coming up right now, people are seeing from a very personal perspective."

How will the internet providers be regulated now?

The FCC did away with rules barring internet providers from blocking or slowing down access to online content. The FCC also eliminated a rule barring providers from prioritizing their own content.

In the absence of a firm ban on these actions, providers will be required to publicly disclose any instance of blocking, throttling or paid prioritization. It will then be evaluated based on whether or not the activity is anti-competitive.

Related: Trump administration sends mixed messages on big media

As part of this shift, oversight of internet protections will shift from the FCC to the Federal Trade Commission.

"The FTC will once again be able to protect Americans consistently across the internet economy, and the FCC will work hand-in-hand with our partners at the FTC to do just that," Pai wrote in an op-ed column Monday.

But consumer advocacy groups have been less than optimistic.

"Not only is the FCC eliminating basic net neutrality rules, but it's joining forces with the FTC to say it will only act when a broadband provider is deceiving the public," Chris Lewis, VP at Public Knowledge, a nonprofit that focuses on the open internet, said in an earlier statement. "This gives free reign to broadband providers to block or throttle your broadband service as long as they inform you of it."

And how will repealing net neutrality affect me?

The concern among net neutrality advocates is that the repeal could give internet providers too much control over how online content is delivered.

Internet providers could choose to prioritize their own content and services over those of rivals. Businesses like Netflix, with large audiences and bank accounts, will likely be able to adapt -- but smaller companies may struggle to strike deals with providers and pay up to have their content delivered faster.

"Those 'fast lanes' will put those who won't or cannot pay in the slow lane, making the internet look a lot like cable TV," Gigi Sohn, a counselor to former FCC chairman Tom Wheeler and a staunch supporter of net neutrality, told CNNMoney.

The repeal could also change how customers are billed for services, both for good and bad. T-Mobile (TMUS), for example, was criticized by net neutrality supporters for effectively making it cheaper for customers to stream videos from Netflix and HBO, putting other video services at a disadvantage.

Without net neutrality, internet providers may pursue similar offers more aggressively. Initially, this might be viewed as a positive by consumers looking to save money on their streaming media.

Yet, some fear it's also possible internet providers will one day effectively charge customers more to access services like Netflix that are currently included as part of your monthly bill.

Not much is expected to change right away, however, as the possibility of legislation and litigation looms.

Is there a chance the repeal is, well, repealed?

The Senate passed a measure to preserve the net neutrality rules last month. On Thursday, with the official repeal date looming, dozens of senators sent a letter to House Speaker Paul Ryan urging him to schedule a vote on the issue.

But the Republican-led House, and President Trump, are both thought to be unlikely to back the Senate's measure.

More than 20 states have filed a lawsuit to stop the net neutrality repeal. Several states, including New Jersey, Washington, Oregon and California, have gone so far as to push legislation to enforce the principles of net neutrality within their borders.

This local legislation could lead to a legal showdown, however. The FCC order that just took effect asserts authority to prevent states from pursuing laws inconsistent with the net neutrality repeal.