If youre interested in what it takes to grow a business from 10 users to 10 million, you should check out this collection of Andrew Chens most compelling writings on viral marketing. Youll learn how to conduct awesome A/B tests and how to find out exactly what your customers truly want from your product. Excerpt Product design fact: A small number of features are used a lot, and most features are never used. This idea comes from one of my favorite books, Designing Interactions, where theres a discussion by the original interaction designer for one of the first/best mobile OSes, PalmOS. He talks about the idea that users interaction with products follow a Power Law distribution- a small number of features are used constantly by users, and then theres a long tail of features that most people dont interact with at all. This is an important idea, because it helps define what good functional design should look like. Good design Good interaction design means giving features prominence based on their usage level- this means some features are basically hidden, whereas some should be in your face. Using Palm as the example, youd want to make Add contact to addressbook prominent but Remove contact should be very subtle- possible, but almost hidden. This means users will be able to pick out what they want to do, most of the time, and occasionally can pick out the corner case. Open design On the other hand, designing your product to be open and a platform means that you want to make anything possible. This often comes with its own design risks, because features arent shown to the user at the priority level associated with their usage. Thats why I find that open systems like Android, Windows, and the Facebook platform can have very messy interactions as a result. An open platform means that a lot more is possible, but the best experiences are watered down by its desire to support an infinite number of possibilities. A more curated experience means that the best experiences can be meticulously designed, but it becomes harder to make all the combinations possible. Constraints start to dominate, but if the constraints are picked well, the experience is better off. Different POVs You can read this post as a discussion of Apple versus Google versus Microsoft, or you can think of it as different design philosophies for how to build products. Both are great, and can lead to fantastic things, but open versus curated can lead to very different outcomes.