There are many different definitions of the concept, but the one that we find most helpful is the following:
Social innovation is a new solution to a social problem that is more effective, efficient, sustainable, or just and that benefits society rather than individuals. Social innovation can be a product, production process or technology, but also a principle, an idea, a piece of legislation, a social movement, an intervention, or a combination of them. (cf. Phills, James & Deiglmeier, Kriss & Miller, Dale. (2008). Rediscovering Social Innovation. Stanford Soc. Innov. Rev. 6.)
Good projects include some element of social innovation. How exactly that is implemented is entirely up to the project organizers, and, thanks to the broad definition of the concept, can take on many different forms.
Find Phills, Deiglmeier and Miller’s full paper on ResearchGate:
https://www.researchgate.net/publication/242511521_Rediscovering_Social_InnovationSocial innovation projects can come in various shapes and sizes. “Solidarity now” is an example from Roskilde Festival 2019: