Regulations come into force at midnight tonight, which allow the British Library to begin archiving the entire UK web domain.
Billions of webpages, blogs and e-books will also be preserved in order to document the digital age.
The library could eventually collect copies of every public Tweet or Facebook page in the British web domain.
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The high of 35C was recorded on a Bakerloo line train between Piccadilly Circus and Oxford Circus at 2pm.
Weather forecasters say temperatures could reach 35C, beating the previous record of 34.6C in the scorching summer of 1976.
After years of political manoeuvring over the future expansion of Heathrow Airport, there has been an important development this lunchtime.