During brainstorming sessions participants may meet around a whiteboard and use Post-its to indicate new ideas and combine similar concepts. It was just such a brainstorming session that inspired the creation of a popular new online digital organizing tool.

That’s the origin story behind Trello, according to a recent interview with founder Michael Pryor in Entrepreneur. Trello gives users an online space with shareable, searchable cards that can be moved between lists, making for an organizing system that mirrors the brainstorming process.

Launched four years ago, Pryor intentionally allowed users to figure out the application on their own, in order to drive user-based creativity in how the product gets used. In fact, the company launched with no marketing budget, but hoped that making the app available for free would boost the spread of the app through organizations. So far the process seems to be working, with 10 million users already on the platform, creating systems for everything from planning vacations to launching new products.

According to Pryor, the idea behind Trello was to make it more than a project management app, but a tool that people could have fun with and use in a wide variety of areas that may not be traditionally thought of as needing project management. Making the process very visual was key; even some tasks that users could do more quickly with drop-down menus are done using drag-and-drop instead, to emphasize the visual nature of the app.

Many users have posted long blogs on how to use Trello, such as a bride who showed how the app helped plan a wedding. Within organizations, teams also use Trello for their project management, letting supervisors easily stay in touch with their progress online. This allows managers to spend less time on project management that the team can share, and more time on supporting staff development.