Basics

If software is the cake, then the source code is the recipe for that cake. A proprietary system is like a cake made by a bakery. We can purchase the cake and enjoy it, but we can’t have access to the recipe. That is usually OK, but what if we like the cake but need to change something about it, let’s say because we are allergic to nuts for example. The recipe gives us the opportunity to change the cake for our own needs (or a whole community of people with similar needs). It isn’t even necessary to know how to bake to appreciate the access to the recipe, because someone else could modify and bake the cake - we could even pay someone to bake the cake for us. Access to the recipe makes the difference though. So it is with open source software (OSS).