The UK is the largest online shopping market in Europe, but there is still room for growth as online sales catch in-store sales.
About E40bn will be spent by UK consumers online in 2014 if sales increase by 10% every year from this year.
E24.7bn was spent online in the UK last year, and an additional £3bn is expected to be added each year for the next five years, according to research from Forrester Research.
The research, entitled "Western European Online Retail Forecast, 2009-2014", found that UK citizens are more prolific online shoppers than continental Europeans, with 48% making a monthly online purchase compared with the European average of 32%.
But online sales are not only a fact of life for consumers. Retailers are becoming more reliant on online sales, and companies such as John Lewis are investing heavily in integrating online shopping with traditional channels.
"Much of the overall retail sector's growth in the US and the EU over the next five years will come from the internet," said Sucharita Mulpuru, vice-president and principal analyst at Forrester Research.
"To maximise that growth, e-business professionals will have to help enable a multichannel strategy that responds to consumers' increased desire to hop between the offline and online worlds and their increasing mobile and social behaviour. The retail innovators over the next five years will demonstrate customer enablement across all touchpoints, not just via a PC-based web browser."
Christmas shoppers spent £1.4m online in a single minute on 7 December 2009 as the digital high street boomed. The day, dubbed Manic Monday, was the biggest ever for online shopping in the UK.