Ad tech is the business model that underpins the internet.
Most websites and apps may be free to use,
but they make money by displaying digital advertising
targeted specifically at you.
An entire industry has grown up around auctioning and targeting
online adverts as accurately as possible
using data collected about each and every user.
Whenever you visit a website, your computer
can send out personal data to thousands of ad tech companies.
They take the information and use it to bid for the adverts
that you see when the page loads.
It takes milliseconds.
Billions of bid requests are made each week in the UK alone.
Europe's entire digital ad market hit 55.1bn euros
in 2018.
But Europe's new privacy law, the General Data Protection
Regulation, has put the industry under a spotlight
because of the troves of personal data it trades.
And not just between the website and an advertiser,
but between advertising companies
that are building profiles of us.
A damning report from the UK data protection regulator
found that the ad tech industry was breaking the law
by illegally collecting and bartering
in special category data which requires our explicit consent.
The regulator has given the ad tech industry six months
to clean up its practices.
That deadline expires in December 2019.
The industry must decide.
Can it legally continue to auction off our personal data,
or must it change its ways to be more transparent
and to minimise how much data it collects?