An age-check scheme designed to stop under-18s viewing pornographic websites will come into force on 15 July.
From that date, affected sites will have to verify the age of UK visitors.
If they fail to comply they will face being blocked by internet service providers.
But critics say teens may find it relatively easy to bypass the restriction or could simply turn to porn-hosting platforms not covered by the law.
Twitter, Reddit and image-sharing community Imgur, for example, will not be required to administer the scheme because they fall under an exception where more than a third of a site or app's content must be pornographic to qualify.
Likewise, any platform that hosts pornography but does not do so on a commercial basis - meaning it does not charge a fee or make money from adverts or other activity - will not be affected.
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https://www.bbc.co.uk/news/technology-47960775