The document summarizes closed source and open source operating systems. It provides examples of closed source systems like Microsoft Windows, iOS, and examples of open source systems like Linux and Android. For each operating system, it discusses their key advantages and disadvantages. Microsoft Windows advantages include direct vendor support but disadvantages are inability to edit code and high costs. iOS advantages are performance and security but disadvantages include being costly and proprietary. Linux advantages are being free, secure, and customizable, but it can be less user friendly than Windows. Android advantages are multitasking and easy access to apps, but disadvantages include ads, wasteful battery usage, and potential for viruses. The document also includes short code snippets to illustrate source code examples for