What does "edge" mean in the repository?

[Marxsal]

We're told that if we problems with the main image we should try edge.

I'm wondering what "edge" represents? That is, if I wanted to build the edge version, what would I do? Is it a development branch?

Thanks!

[kagahd]

edge : built from the current state of master. This might break from time to time.
See: https://github.com/bpatrik/pigallery2/blob/master/docker/README.md?plain=1#L7