For example, many buyers of Home Depot grills and patio furniture go to a store to get the advice of a shop assistant, but buy on their smartphones then and there so they can get home delivery and avoid carrying the items themselves.
Across the sector progress on synchronising the digital and the physical has been mixed, whether it is with advertising, pricing and demand forecasting or customer call centres and deliveries. In a June survey, Retail Systems Research asked retailers whether they were synchronised in 13 different areas and in each one fewer than one in five said yes.
Many retailers have been hampered by their first attempt at ecommerce several years ago, when they set up online operations as standalone businesses with separate technology.
Since then some of the biggest have sought to buy skills by acquiring tech start-ups. A year ago Home Depot acquired Black Locus, a retail analytics group, and this year Walmart bought four companies—Torbit, Inkiru, OneOps and Tasty Labs—whose software crunches large amounts of data and speeds up websites.
In October Staples, the office-supply chain, bought Runa, whose tools personalise special offers. "We're not a tech company, so we need to think like a tech company," says Faisal Masud, executive vice-president of global ecommerce at Staples.
Staples is ranked as the US's second biggest online retailer by the Internet Retailer website as its $10.3 billion in online sales globally last year—just over 40 per cent of its total—were second only to those of Amazon, whose total is expected to hit $75 billion this year.
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Popular initiatives include capturing consumers from social media websites such as Facebook and Pinterest, and creating in-store smartphone apps that let shoppers locate what they want, read reviews, and in some cases make a purchase.
But retailers are devoting more effort to deliveries, whose speed and reliability have become a key battleground in ecommerce today, due largely to the standard set by Amazon.
More retailers are using stores to fulfil online orders, either by letting customers "click-and-collect" from their nearest shop, or by shipping products from shops—as opposed to warehouses—to their homes.
Macy's, a department store chain that is building its fourth ecommerce warehouse, has also turned 500 of its 840 stores into additional shipping facilities, putting counters into store rooms where the employees who stock shelves also pack online orders into boxes.
Retailers say such moves are about offering maximum convenience to shoppers, but Sucharita Mulpuru, analyst at Forrester Research, points out that, as shipping costs become painfully high, using stores as mini-warehouses also saves money.
Mr Masud at Staples says: "Having stores and online is a huge benefit, but only if you leverage those resources . . . If you don't have a fully integrated experience, those assets are not utilised."
—By Barney Jopson with the Financial Times