Disclaimer: Currently I am employed by Microsoft, but my views and thoughts are still my own. The reason I joined Microsoft was, the work Microsoft have been doing for last couple of years in Open Source Space. Today I am a advocate for Open Source representing Microsoft.
In August 2016, Microsoft released Windows Subsystem for Linux (WSL) as part of Windows 1607. At the time, WSL had some performance issues, but you could run Linux applications on Windows without the need of either a VM or dual boot.
Now with the release of Windows 2004, Microsoft has released a new version of WSL2. This time around, Linux is running inside a invisible nano VM, without the need of a full-fledged hypervisor (i.e. Hyper-V). WSL2 is "Windows Hypervisor Platform". Due to the fact, there is no need for full installation of Hyper-V, WSL2 can on Windows 10 Home, Pro and Enterprise.
WSL2 also provides a new backend for Docker. Which makes it easier to work with docker in Windows 10 Home, without sideloading a MobyVM (or any other Linux distro with Docker) in VirtualBox.
WSL2 brings almost bare metal performance to the subsystem, and makes WSL more usable. Now you can run Linux apps on Windows, as if they were running natively (well they are sort off).
Update: At //build 2020 Microsoft announced support for GPU and GUI applications is on the roadmap for WSL2.