Linux Distributions
Familiar commercial operating systems Windows and MacOS tightly couple their kernels with their user-space operating system components like system utilities and desktop environment. In contrast, Linux follows a mix-and-match philosophy; while a user can manually pick and choose which components they want to for their system, most users install one of several hundred Linux distributions, which are largely characterized by their choice of system utilities (also called core utils), which package management system they use to manage installed software, which init system they use to manage system services, and which desktop environment, if any, they come with. Each distribution usually has an associated culture, as well.
For example, Ubuntu is well-known for its user-friendly installation process, stability through periodic versioned releases, and its preconfigured desktop environment with a large amount of additional pre-installed software. Its community is oriented towards Linux novices migrating from, primarily, Windows. In contrast Arch Linux is installed manually via the command line, comes without extra bells-and-whistles, and uses a rolling-release model where software is always on the bleeding edge. Arch’s community tends to have higher expectations from its members to educate themselves on how their systems work before asking for help. And, at the totally other end of the spectrum, Gentoo is famous for providing a barebones system that requires manual configuration from the ground up. While most other distributions’ package managers install software as pre-built binaries, Gentoo uses a source-based package management system so that all software is compiled as it is installed, which allows considerable customization, but also requires considerable expertise.
Distrowatch is a popular website for tracking and comparing Linux distributions.