There have been several different versions of Sass available over the years.
Sass was first created in 2006 using Ruby. However, this version of Sass was deprecated and reached end-of-life in 2019. You shouldn’t use this version of Sass anymore.
The main version of Sass currently is called Dart Sass. As the name implies, this version was created using Dart. Version 1.0.0 of Dart Sass was released in March 2018. Dart Sass is the version you’ll likely want to use when starting a new project.
There was also another version of Sass called LibSass, which was deprecated in 2020. You can read more about it on the official Sass blog.