Wireless broadband hotspots are used by shoppers who need to kill time or want to find a better deal online.
Over half of UK shoppers connect to free Wi-Fi while browsing on the high street.
A survey by broadband and mobile provider O2, which operates its own network of O2 WiFi hotspots in shops and restaurants, found that 58% of people connect to wireless broadband on smartphones and tablets when out shopping.
Killing time while waiting was the main reason for shoppers logging on, but over 20% said they use free Wi-Fi to search for a better deal online.
Gavin Franks, managing director of O2 WiFi, said: "We've created a 'free for everyone' user model that isn't dependent on being a paying customer of either a broadband or mobile network."
"It's designed for the smartphone generation with simple sign-up and seamless connection, which has meant adoption and use has grown rapidly," he added.
O2 WiFi, which has wireless broadband hotspots in well-known high street locations such as Costa Coffee, McDonald's and Debenhams, has recently passed its six millionth customer sign-up.
According to the survey, 39% of shoppers say their choice of shopping destination is influenced by the availability of free Wi-Fi. A further 14% said wireless broadband is an absolute must for them to even think of entering a coffee shop.
One in five claimed they feel angry and frustrated by shops that don't have free Wi-Fi.
Earlier this month, O2 announced its customers would soon have free access to broadband on the London Underground.
It will join EE, Vodafone and Virgin Media - which operates the network - in offering free Wi-Fi at over 100 tube stations across the capital.