This is another out-of-home sector that is still in its relatively infancy - and its evolution has accelerated in the past couple of years as advertisers and media owners have begun to recognise the importance of two related opportunities.
The first is the fact that shopping malls, especially many of the sprawling out-of-town developments, are now regarded as leisure destinations in their own right rather than functional outposts of the domestic routine.
The second is the notion that the retail channel (the myriad in-store opportunities that have emerged in recent years, from trolleys to floor graphics) does not have to begin and end at the retailer's door. It can and should extend from the car-park, though the concourse, up to the till.
Many agencies now have specialist planners in this area. They are developing integrated strategies to target an audience that is attractive in sheer numerical and demographic terms - with the added attraction that it obviously has shopping on its agenda.
Previously, the retail channel was dominated almost entirely by the demands of the retailers and the mainstay was the price-led promotion. Now, more sophisticated strategies are emerging and branding initiatives are moving much closer to the point of sale than ever before.
And the footfall figures are clearly impressive. According to TNS research conducted last year, 55 per cent of UK households shop at Tesco at least once a fortnight - so if you advertise in the vicinity of a Tesco store, your potential reach is enormous.
There are three big supermarket contracts that embrace the opportunities available both outside the stores (mostly six-sheets) and inside them: JCDecaux has the Tesco contract, Asda (the second biggest in revenue terms) is with Titan and Sainsbury's is held by Clear Channel. But the Asda and Sainsbury's contacts are up for tender this year and there has been speculation that the pitch process could signal a significant shift in the balance of power for the first time since the sector emerged as a coherent entity eight years ago.
There would be pros and cons to this: if a single media owner owned this sector, its expertise in getting the best from it could be expected to grow.
The downside would be a decrease in market competition and the concern that prices would rise. However, given the fierce rivalry between the top retailers, such an outcome perhaps seems unlikely.
Equally important in this sector are the multistore shopping malls that can now be found throughout the UK. In one of the biggest contract awards of recent times, Clear Channel's Adshel Retail division consolidated its position with one of the country's top community shopping-centre brands, appropriately named The Mall.
It runs 23 shopping malls from Aberdeen to Bristol to Epsom, which are visited by more than 4.5 million shoppers each week. Overall, Adshel Retail offers six-sheet sites in more than 80 shopping centres.
But the market leader is Titan, which owns 1,700 panels in 102 malls across the country, including Bluewater in Kent, Lakeside in Essex, the new Bullring in Birmingham and the Trafford Centre near Salford.
MAJOR PLAYERS: Titan, Adshel Retail, JCDecaux, Admedia
WHAT'S NEW: The retail channel - an integrated approach that packages together all the media opportunities from the car-park to the check-out till
CASE STUDY - Fairy Fabric Enhancer
Client: Procter & Gamble
Media owner: Adshel Retail, part of Clear Channel UK
Brief: Promote the launch of Fairy Fabric Enhancer from Fairy Non Bio
Target market: Mothers of young children and people with sensitive skin
Sector inventory used: Two hundred and thirty Adshel Retail panels across 65 shopping malls nationwide. The ad ran on Adshel Retail's new "mother and baby" offering, which includes panels close to branches of Mothercare, Early Learning Centre, Gap Kids and Disney Store. The campaign ran for a fortnight in February and again in March.
Wider outdoor inventory used: Six-sheets at Sainsbury's.
Other media used: National TV.