Preparation – This first stage is all about gathering information. This is the stage where you do user research and empathise with the users in order to define the problem and your users’ needs.

Incubation – At this stage, you take a step back from the problem and allow your mind to wander to let it contemplate and work the problem through.

Illumination – This is the third stage. This stage essentially describes the classic “eureka!” or “aha” moment of insight. However, the fact that illumination has an entire stage devoted to it shows that it’s essentially not just a quick moment of insight and helps us understand that it’s something we can—and should—work towards achieving. 

Verification/Implementation – At this fourth stage, you build on the “aha” solution. You evaluate, analyze and build on your idea. You then polish it to make sure that it’s both useful and novel. At this stage, you would also often choose to prototype and test your idea in order to find out if it meets the users’ needs which you defined at the preparation stage—and, if so, polish it as needed.