(This posting reviews a presentation given by Paul Goad, Managing Director of Tacoda, at the Ingenta Trends event in London in December).

Behavioural targetting is gaining traction in the advertising industry. Traditional online advertising values users based on their context, and favours big sites that have their own sales force and connections to networks; smaller providers simply had no way of breaking into these networks. Behavioural targetting, however, values users for themselves rather than for their context. It's the long tail of advertising; small user groups can be monetised much more successfully, enabling smaller site owners to benefit. An understanding of the user's interests enables the site owner to deliver content based on *them*, rather than on the niche interest reflected by the site they are visiting. Behavioural targetting has thus caused an attitudinal shift among agencies and advertisers; suddenly, it's not about *where* an ad is displayed, but about *who* it is displayed to. Publishers can now be rewarded for having built up a community of users.

Behavioural targetting has also extended the areas that advertisers can tap into, beyond the limitations of contextual channels. Agencies such as Tacoda, which provides software and services that support behavioural targetting, can provide comprehensive statistics that not only enable optimisation of advertising strategies but that further help publishers to understand their users, which in turn can help publishers refine web strategies from traffic management to content segmentation.

Simply, behavioural targetting works by categorising the sites within a site owner's network and noting which categories of site are visited by a user. Profiling is anonymous (using browser cookies) and no personal data is collected or stored. Browsing behaviour is monitored and the data is matched into one of many hundreds of profiles. Once the cookie (and thus, the user) has been matched to a profile, appropriate ads are displayed. Site owners have control over the types of ads displayed and can respond to any sensitivities in their userbase; they also benefit financially from contributing the data that helps to build core profiles.