What is Abstract?

The tagline from goabstract.com: "Abstract is a platform for modern design teams to work together"

Okay, but what does that mean?

Shortly after the tagline is a bit more information:

"A secure, version-controlled hub for your design files" - meaning Sketch only, for now.
"One final version" - so simplified version control, where there is only one truth.
"Multiple designers can work on the same file without fear of overwriting changes" - this means resolving conflicts through merges, just like with code!
An activity overview, so that you're not digging through files for information on updates and changes from others (or yourself, if you haven't had your coffee).
User mentions to foster feedback, discussion, and approval.
Builds and extends git as the basis for Abstract.

OMGosh, yes