This question comes up a lot among Ruby beginners so I wrote an article that goes into detail. I explain why it's worthwhile to install a version manager. I recommend asdf for those developing Rails web applications (which require Ruby, Node, and Yarn) or those using multiple languages such as Ruby, Node, and Python. For a simpler version manager just for Ruby, I like chruby. The article provides all the details, explanation as well as instructions. Let me know if I missed anything or anything's unclear. Sharing it here on Hacker News because the community might have suggestions for improvements.