We spoke to Dominic Joseph, the co-founder and CEO of Captify, a company pioneering search retargeting, about the growth in digital advertising, and how advertisers can better use big data to target their customers. Not to mention exactly what search retargeting is – read on to find out.

TechRadar Pro: How much has digital advertising grown over the past year compared to traditional advertising?

Dominic Joseph: More and more advertisers are evolving their campaigns in line with digital innovations in the industry, so much so that this year, digital will account for almost half of all UK ad spending. At the same time, newspaper ad spend is to fall below the £1bn (around US$1.68, AU$1.82bn) mark for the first time this year, which highlights the huge impact that digital is having on the advertising world. What advertisers need to do now is ensure their investment in digital is being spent wisely, so that they are getting their ads in front of their intended audience every time.

TRP: What factors are driving advertisers to convert more spend to digital?

DJ: Our changing media consumption habits are having a huge impact on which channels advertisers are allocating more budget to. The average British adult spends one in 12 of their waking hours on the internet. Some advertisers see this as a chance to push their brand in front of as many eyeballs as possible, and as a result, people are being subjected to increasing numbers of digital ads.

TRP: Why are marketers increasingly using big data to target their audience?

DJ: As the time that we spend online increases, so too does the amount of data we're generating. Today, the average family generates enough data to fill 65 iPhones each year, and this is set to increase fivefold by 2019. To put this into context, every two days in 2014, we create the same amount of information as we did from the very beginning of time up until 2003.

Undoubtedly, the sheer volume of data generated by each individual could overwhelm number-crunching marketers. Utilised effectively however, it can help marketers gain a far deeper insight into their customers' previous buying behaviours, and brand preferences. Focusing on specific data sets will enable marketers to pinpoint individuals rather than broad audience groups.

TRP: What tech tools are advertisers using to automate media buying?

DJ: Programmatic buying is an automated marketplace (controlled by humans) that gives advertisers an efficient way to scatter their display ads far and wide for relatively little investment. Just like a stock exchange, it relies on automated systems and algorithms to sift through huge volumes of data. Automatic bids for digital space on ad marketplaces are then placed in real-time.

The programmatic industry is still in its infancy, and as a result, there are some inefficiencies that advertisers should be aware of. For example, programmatic buying only allows advertisers to create broad, pre-packaged audience segments. Also, because of its "scattergun" approach, it doesn't let them have complete control over where their ads will appear and in front of whom, and therefore often results in wasted budget. However, there are some clever new technologies that advertisers are using to help them get down to a much more granular level of data analysis.

TRP: Why don't broad data sets work?

DJ: Not every 20-something professional male will be in the market for a brand new sports car and so serving ads for the latest model to every male in this demographic is unlikely to result in thousands of click throughs. In fact, serving an irrelevant ad to a consumer may have the opposite effect. Imagine if that individual has just ordered a new car, and then sees an ad for a better deal; or what if they were simply doing some research into the industry? Being subjected to an irrelevant banner ad time and time again could frustrate the consumer and turn them off from online ads for good.