At the time of writing, WhatsApp - the social messaging app owned by Facebook - doesn't present ads. But that might not be the case come 2021, as Facebook reportedly eyes-up ways to present targeted advertising, following the ongoing unification of its messaging apps.
The ad-free model wasn't always the case though: before Facebook acquired WhatsApp in early 2014, users had to the option to pay for ad-free use, typically at a rate of $0.99/£0.79 a year (other options were also available). Remember that?
This revenue model actually continued at the beginning of Facebook's ownership before, in 2016, it went completely ad-free. Facebook has confirmed on multiple occasions that its ongoing intent was to keep it an ad-free platform - wishes that WhatsApp's founders wanted to maintain, following sale of the company.
But times are changing and it looks as though adverts will make a comeback, according to reports, with Facebook to identify associated mobile numbers between Facebook and Whatsapp accounts in order to present targeted ads.
However, as WhatsApp still sold five-year ad-free plans in 2016, we can't see how this could be possible before 2021. Perhaps more a case of 'when', not 'if', then?