The short version
A microdrama is a scripted series shot vertically for phones and told in very short episodes, usually around a minute, each one ending on a turn that makes the next one feel mandatory. A full series can run sixty, eighty, sometimes over a hundred episodes.
You will see the same thing called a vertical series, vertical drama, or short form vertical series. They describe the same format.
Why vertical, and why about a minute
Vertical because that is how a phone is already in your hand. Turning the device is a decision, and every decision is a place a viewer can leave.
About a minute because it is long enough to land one real turn and short enough that stopping has to be a choice rather than a drift. The structure is closer to a soap opera than a short film: continuous story, constant escalation, and a cliffhanger as a matter of course rather than a flourish.
How a microdrama differs from a short film
A short film is finished. It makes its point and ends. A microdrama episode is deliberately unfinished, and the satisfaction is in continuing rather than concluding.
That changes how you write it. There is no room for a slow open, and no room for a scene that only exists to move a character across a room. Every episode carries a hook, a turn, and an exit.
Where the format came from, and where it is going
The form grew out of serialised mobile fiction and found its audience where people already read and watch, which is on a phone during the gaps in a day.
What is still being decided is who it belongs to. Urban Operas produces Black microdrama, written, cast and shot for an audience that was already watching this format before anyone built a home for it.