Open Source Code
The term “open source” refers to a practice, philosophy or methodology of production, that gives users a free access to the end product's source materials, namely the source code. That the source code is accessible to the users, means that they can see it and modify it. The community controls the official product so that no bad code will enter it, but anyone who downloads a version of any open source software, also receives the source code, and can edit it to his use in the way he wants.
Open source is not so much about technology as it is about licensing: it means, that the use of the intellectual means of the production isn't restricted or is very little restricted. Thus, the open source as a way of production is not tied to the computers and technology, and has its origins in time way before computers. It is a way in which the productive community organizes the possibilities to use of the sources of production, namely, that it leaves the use of most of them free, in the sense of commons. That something is common, it means that is in joint use or possession, or in other words: not controlled, or very lightly controlled. It doesn't necessarily mean that their use would be free of charge or they could be used arbitrarily by anyone.
For example, if the seas would be commons, we would still want to restrict their use for dumbing toxic waste in order to keep them usable for others, and a pay could be demanded for the use of the seas, in order to keep the use low enough. Even a permission for fishing can be asked, but it should be possible to anyone to get. Main point is, that seas would be in common use: anyone could use them. For similar reasons some ways of fishing would be restricted too. However, there would be no fishing licenses given to specific persons and areas, but we would all be free to use the seas, only with restriction that we wouldn't damage the seas. In the world of Internet, some services and programs that are built on open source code, may be not free of charge, but you do get the source code with the program, so you can see what you're getting and develop it. A common restriction is that when taking an open source code and developing it for your own means, you must, when selling or sharing it, give your own new source code freely with it. This is a reasonable restriction, because it merely evades the situation where someone would take the advantage on the open source community while not sharing his own code.