A "design jam" -- also known as an "idea jam", a "nerd jam" or simply a "jam" -- is a collaborative brainstorming activity or event, geared towards generating solutions in a fun and creative environment.
Problems and Purpose
A design jam is a collaborative brainstorming activity or event, geared towards generating solutions in a fun and creative environment. Jams can be self- or group-initiated, or planned in advance and facilitated. The format of a jam is flexible to the problem that is being addressed.
The Vancouver Design Nerds outline the purpose of a design jam as follows:
- Collaborative Rapid Idea Generation
- Participant Empowerment
"A Design Jam is an idea factory. It’s a fun, fast, creative brainstorming session intended to create a range of diverse visions that address an issue. In the design, architecture and urban planning fields, Jams are employed as one of the many stages of a larger planning, strategy and design process undertaken by the lead design organization and stakeholders involved in a project. By changing the way we think and interact, we change the way we behave and respond to complex problems, therefore creating the social, urban and environmental transformation we seek." 
Origins and Development
Rooted in design thinking theory made popular by the internationally renowned design studio IDEO, divergent idea generation is widely accepted as a critical phase in the design process. As design thinking became more mainstream, organizations such as the Design Nerds emerged and systematized multiple iterations of group brainstorming processes that are adaptable to multiple design contexts and stakeholder groups, dubbed: "nerd jams".
Jams have been also implemented by municipal governing bodies and civil society groups to empower citizens to be part of the generation of ideas and solutions. This is a departure from more traditional community consultation models, where solutions are proposed and feedback is requested. One such example in the Canadian context is the "Engaged City Task Force", launched by the City of Vancouver, when it hosted a series of public jams to generate citizen solutions to issues such as social isolation. 
Participant Recruitment and Selection
Jams can be events that are open to the public, or for closed groups of selected stakeholders. Jams work best when there are multiple participants, and facilitated jams flow more smoothly when there is at least one facilitator for every 5-8 participants in breakout groups.
How it Works: Process, Interaction, and Decision-Making
A combination of idea "pitching", dotmocracy for concept selection, and breakout groups make up the typical process elements of a jam. Breakout groups work independently to generate solutions to pitch back to the wider group. Sometimes this process is repeated, with a mixing of groups and additional dotmocracy rounds in between. Ideally, food and beverages are provided, along with substantial breaks to allow for socializing and conversations among participants. The balance of informal and formal activity and the element of fun within a jam is what differentiates it from a more traditional engagement process. 
Influence, Outcomes, and Effects
Some revolutionary ideas have been imagined during jams, and many have been realized, including successful business models, follow up projects, and even public art installations. Depending on the jam and stakeholder needs, a report can be generated to summarize the ideas that emerged during the event. This can have downstream influence in the decision-making process of local governments or trigger follow-up action by stakeholders.
Analysis and Lessons Learned
A common critique of the process is that ideas generated during jams sometimes do not go anywhere. If the stakeholders or participants are not motivated to follow up, no one is responsible for ideas being taken forward and they may be lost. It is therefore critical that some level of post-jam oversight and accountability is in place before the process is started.
 Vancouver Design Nerds (2020). What is a design jam? www.vancouver.designnerds.org/nerd-jams/
 City of Vancouver (2013). Vancouver Mayor's Engaged City Task Force. https://vancouver.ca/files/cov/Engaged-City-Task-Force-Quick-Starts-Report.pdf
 OIDP 2017 Montreal Actes de la Conference (2017). Appartenance et Participation Creative. http://www.oidp2017mtl.com/sites/oidp2017mtl.com/files/appartenance_et_participation_creative_16-06-17.pdf
 Ideo. (n.d.). www.ideo.com/
 Design Nerds (n.d.). www.designnerds.org/
Photo: courtesy of Vancouver Design Nerds http://vancouver.designnerds.org/nerd-jams/