Acorn is a way of organizing intended Goals and Outcomes on a tree. You can think of it as a virtual whiteboard for collaborative planning. Acorn creates an Agile process based on the Deming Plan/Do/Check/Act cycle, that is less bound to some of the traditional dependencies of Scrum and more applicable to projects and organizing beyond software development. The patterns Acorn enables and the resultant State-of-Affairs trees are scalable, handle complexity and uncertainty, and work with distributed groups.
Acorn could have many uses, and one that it has served is organizing the vision and work allocation of distributed teams of software developers. Other uses could be as a personal planning tool, for teams completely aside from software, or anything where linked/inter-related nodes in a structured form would be helpful.
Acorn was envisioned and prototyped (using a third party platform) by the Holochain core development team in 2018 to organize their own planning and execution process.