
Alpine Linux

Alpine Linux is a Linux distribution based on musl and BusyBox, designed for security, simplicity, and resource efficiency. It uses OpenRC for its init system and compiles all user-space binaries as position-independent executables with stack-smashing protection.
Because of its small size, it is commonly used in containers providing quick boot-up times.
History.
Originally, Alpine Linux began as a fork of the LEAF Project. The members of LEAF wanted to continue making a Linux distribution that could fit on a single floppy disk, whereas the Alpine Linux wished to include some more heavyweight packages: Squid and Samba. They also add security features and a newer kernel.
Features.
Alpine uses its own package-management system, apk-tools, which originally was a collection of shell scripts but was later rewritten in C. Alpine currently contains most commonly used packages such as GNOME, Xfce, Firefox, and others.
Alpine Linux can be installed as a run-from-RAM operating system. The LBU (Alpine Local Backup) tool optionally allows all configuration files to be backed up to an APK overlay file (usually shortened to "apkovl"), a tar.gz file that by default stores a copy of all changed files in /etc (with the option to add more directories). This allows Alpine to work reliably in demanding embedded environments or to (temporarily) survive partial disk failures as sometimes experienced in public cloud environments.
A hardened kernel was included in the default distribution for up to and including Alpine 3.7, which aids in reducing the impact of exploits and vulnerabilities. All packages are also compiled with stack-smashing protection to help mitigate the effects of userland buffer overflows.
By default, it includes patches that allow using efficient meshed VPNs using the DMVPN standard.
It has reliably had excellent support of Xen hypervisors in up-to-date versions, which avoids issues as experienced with Enterprise Distributions. (The standard Linux hypervisor KVM, is also available.)
It allows very small Linux containers, around 8 MB in size, while a minimal installation to disk might be around 130 MB. 
Alpine Configuration Framework (ACF): While optional, ACF is an application for configuring an Alpine Linux machine, with goals similar to Debian's debconf. It is a standard framework based on simple Lua scripts.
It previously used uClibc as its C standard library instead of the traditional GNU C Library (glibc) most commonly used. Although it is more lightweight, it does have the significant drawback of being binary incompatible with glibc. Thus, all software must be compiled for use with uClibc to work properly. As of 9 April 2014, Alpine Linux switched to musl, which is partially binary compatible with glibc.
The lightweight OpenRC is the init system currently used by Alpine Linux. Unlike many distributions, including Debian, Ubuntu, RHEL, Arch Linux and CentOS, Alpine does not use systemd.