MEPs are due to vote on major changes to copyright law, which has divided experts and proved controversial.
Former Beatle Sir Paul McCartney has written to politicians urging them to support the changes.
The new law would put a greater responsibility on individual websites to check for copyright infringements.
But the web's inventor Sir Tim Berners-Lee and others have expressed concerns about the proposed rules, which they say threaten internet freedom.
What are they voting for?
The Copyright Directive is intended to bring rules around content in line with the digital age.
The two most controversial parts of it are Article 11 and Article 13.
The first of these is intended to provide fair remuneration for publishers and prevent online content-sharing platforms and news aggregators sharing links without paying for them. But it has been called the "link tax" by opponents and raised questions about who will have to pay and how much.
Article 13 puts more onus on websites to enforce copyright laws and could mean that any online platform that allows users to post text, images, sounds or code will need a way to assess and filter content.
Who supports it?
Supporters of the rule changes say they would improve copyright rules, giving intellectual-property protection to news and video content.
"Today, some user-upload content platforms refuse to compensate artists and all music creators fairly for their work while they exploit it for their own profit," reads the letter from Sir Paul McCartney.
"The proposed Copyright Directive and its Article 13 would address the value gap and help assure a sustainable future for the music ecosystem and its creators, fans and digital music services alike."
Centre-right German MEP Axel Voss is in charge of pushing through the legislation and recently published a video intended to counter what he called "fake news" about the legislation.
He said the reaction to the law was "going beyond what is acceptable".
"We will not end the internet," he added.
Who opposes it?
Critics claim that Article 13 could have a massive impact on how people use the internet, putting paid to memes and remixes.
In particular there are concerns that it will require websites to scan all content being uploaded, automatically blocking anything that might infringe copyright.
The use of artificial intelligence in filters could mean they will not be able to distinguish between content that infringes copyright and fair use, such as satire and memes, they say.
A petition against the change - known as Save Your Internet - has gained 750,000 signatures.
And a letter signed by 70 influential technology leaders, including Vint Cerf and Tim Berners-Lee, described it as an "imminent threat to the future" of the internet.
Italy Wikipedia shut down for a day earlier this week in protest at the plans, which co-founder Jimmy Wales has described as "disastrous".
The editors wrote that "Wikipedia itself would be at risk of closing", reports BBC.
"If the proposal is approved, it may be impossible to share a newspaper article on social networks or find it on a search engine," it said.
What happens next?
After the vote, the legislation is set to be debated in closed-door discussions between EU legislators and member states - but MEPS will have the chance to object to this.
The so-called trilogue negotiations are intended to speed up the process of laws being adopted - but some say this is undemocratic.
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