Online users are leaving internet passwords in their wills as Britons amass a £2.3 billion digital inheritance, new research suggests.
A poll of 2,000 adults found 25% had more than £200 worth of films, video and music stored online.
Nearly a third considered the sum valuable enough to be passed on to loved ones and 11% have already put internet passwords in their wills.
Without the passwords being included in wills, billions of pounds' worth of films, music and pictures stored in "cloud" services such as Hotmail, Facebook, iCloud and Flickr would be lost.
The research, by cloud computing company Rackspace, found that 53% of those polled held "treasured possessions" in such services.
A quarter said they had "special photos" stored online, one in 10 had treasured videos and the same number kept sentimental emails from loved ones.
Lawyers described the passing on of valuable passwords as a major change to the traditional way wills have been drawn up.
Matthew Strain, partner at London law firm Strain Keville, said: "With more photos, books, music and so on being stored online and in digital format, the question of what happens to these when people are gone becomes more important every day.
"People have not yet come to grips with the value of these digital possessions and the risk is that they may be lost if the owner dies, or even that their estate may be liable for ongoing subscriptions to online magazines or newspapers, for instance.
The study also revealed 66% relied on cloud computing services every day without realising it. By 2020, a third are expected to store all music online while a quarter said all their photos will be kept online. One in seven also said they would no longer own books and will instead read e-books.