Brainstorming is famous, it's the superstar of all creative techniques. Frustrated by employees’ inability to develop creative ideas, Alex F. Osborn began hosting group-thinking sessions and outlined his method in the 1948 book Your Creative Power. Brainstorming combines an informal approach to problem solving with lateral thinking to produce new ideas and is based on four rules:

• Generate as many ideas as possible
• Prioritize unusual or original ideas
• Combine and refine the ideas generated
• Abstain from criticism during the exercise.

Brainstorming is a two-step process with a divergent and a convergent phase. Each step can be done collaboratively or not and the second step is often made after the collaborative session.
During the divergent phase, people should suspend their judgement to generate wild and original ideas. Some of these ideas can be crafted into creative solutions, while others will only spark other ideas.
Brainstorming is very good to diverge and find new solutions but you must have a plan to review ideas and converge on concrete solutions. This can be part of the session or something you do afterwards. Whatever your plan is, share the review conditions with your group. It's important for your team to feel that their ideas will be useful and considered.

It's still important to start your brainstorming session with a clear definition of your challenge if you want to avoid unrelated ideas. You can also define the context and give many insights to your participants. Your group should be well-balanced between expert and layman according to the outcome expected. If you want radical and very original ideas, it can be interesting to have experts of an unrelated field in your group, but don't expect good solutions if your group don't have the basic keys to understand your challenge.

The brainstorming can fuel your creativity if it well organized but it can also have some flaws you must avoid. People produce less ideas if they fear criticism, if there is a political leadership in the group, if they don't feel concerned or if they have to wait to express their ideas. Despite these flaws and many studies that claim that individual ideas are better, brainstorming is widely used in organization. Regardless of the quality, a shared idea is more likely to be implemented than an isolated idea. Moreover, problem-solving benefits from different types of knowledge and thinking. Even if the process doesn't seem frictionless, it takes a company to raise an idea.

This article from Harvard Business Review explains that online brainstorming like Stormz allows you to avoid political and group bias by giving anonymity and giving attendees the possibility to freely express their ideas. Online brainstorming is also scalable and bring all the features we used to have in social networks like asynchronicity, comments and likes.