Operating System (OS)
An operating system is the core software layer that manages a computer's hardware resources and provides a stable interface for applications to run on. It schedules tasks, enforces security policies, handles file I/O, and mediates all interactions between software and the physical machine.
What if your OS isn't just doing that?
Because the OS sits above everything that runs on the device, it has privileged visibility into all processes, files, network connections, and user actions. If the OS, or an "OS-level" service, logs or transmits this information, it creates a single, powerful point of surveillance to monitor a user.
Data could be abused by malicious actors, exploited for targeted advertising, or misused by state or corporate actors. In essence, the OS can "see" everything, so any data-collection feature risks turning the system into a comprehensive overseer of the user's behavior.
With proprietary operating systems, it's really hard to understand what impact those features have.
In contrast, systems that are open-source let you inspect and audit what runs your device.
Recommendations
📄️ Desktop
In GNU/Linux distributions, GNU supplies the core tools and libraries (editors, compilers, utilities) that run on top of the Linux kernel, which manages hardware and low-level system functions. A desktop environement (e.g., GNOME, KDE, Xfce) is a set of free-licensed graphical components that sit on top of GNU/Linux, giving users a complete, modifiable operating system.
📄️ Smartphone
Smartphones are often considered a powerful tool for staying connected, but fundamentally, they are a spying device. They come with a set of cameras, microphones and geo-spatial positioning devices. As an example, when the NSA was in the process of developping DROPOUTJEEP, a iOS backdoor, the particular attractiveness of these hardware features is evident.