HTML5 ads are the replacement for Flash-based ads that designers often built when they wanted to use animations or interactivity in their creative. Flash was used extensively from the early 2000s through to 2016. Flash support started falling considerably after 2010 due to mobile operating systems like Apple’s iOS not supporting Flash, and Google’s Android having limited support.
One of the biggest marketing challenges that brands and agencies face is the gap between programmatic and creative. An article by Yuyu Chen, from Digiday highlights that 30% of the attendees of their Programmatic Summit identified this as their top concern (see link at the bottom).