What was the original name of the Windows Subsystem for Linux?

The original name of the Windows Subsystem for Linux was Bash on Ubuntu on Windows. Microsoft introduced the feature in 2016 as a way to run Ubuntu's Bash shell and Linux command-line tools directly inside Windows 10.

The name reflected the first release's limitations: Ubuntu was the supported Linux distribution, and Bash was the main interface users were shown. The feature was initially a beta component of Windows 10 version 1607, also known as the Anniversary Update.

Microsoft later adopted the broader name Windows Subsystem for Linux, or WSL, as the technology expanded. WSL stopped being a beta feature in Windows 10 version 1709, when Microsoft added support for multiple Linux distributions through the Windows Store.

A common mix-up is treating WSL 1 as the original name. WSL 1 describes the first underlying architecture, while Bash on Ubuntu on Windows was the early public product name. WSL 2, introduced later, uses a lightweight virtualized Linux kernel and offers much greater system-call compatibility.