About 3,200 UK charities and businesses are expected to generate millions of pounds for good causes during today's Giving Tuesday.
Giving Tuesday originated in America as an annual day to encourage giving and now occurs in more than 60 countries.
The Charities Aid Foundation, which describes Giving Tuesday as the antidote to Black Friday, has led the initiative in the UK for six years.
This year's activities include the online match-funding initiative The Big Give attempting to raise more than £14m from what it hopes will become the country's biggest-ever match-funding campaign. Its week-long Christmas challenge begins at noon today.
Companies participating include RBS, Samsung, PayPal and BT.
"Last year celebrities including Sir Richard Branson, Cara Delevingne and Dua Lipa all got behind the campaign," said Gráinne Mathews, Giving Tuesday UK lead at CAF.
"£7.8m was raised in the UK on the day, and that’s just donations collected online."
In London, Giving Tuesday messages will be beamed on the top of the BT Tower throughout the day and the media company Thomson Reuters will be publicising the campaign on its Canary Wharf Jumbotron screen.
Paypal will match-fund up to a total of £150,000 on the day. RBS will match its staff’s payroll-giving contributions and promote Giving Tuesday to more than 1.5 million of its customers.
The RSPCA is using the day to urge people to use AmazonSmile, a website set up by Amazon with the same products, prices and features, but which ensures that Amazon donates 0.5 per cent of the price of eligible purchases to a charity of the customer's choice.
The RSPCA has raised £100,000 from the site since it became one of the first charities to sign up to it two years ago.
Up to 15 staff at the Youth Sport Trust will cycle 108 miles, broken down into stages, to show support for Ben Smith, an ambassador of the charity who plans to cover 14,001 miles in the US on foot and bike next year to raise £1m for the organisation.
Reason Digital, a digital social enterprise, has invited service users from its charity partners to create one-minute films that raise awareness of their work, which will be released every working hour throughout the day.
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