Ruby is installed on a macOS for local development, avoiding pre-installed Ruby versions that are outdated and may conflict with Homebrew or other installations. The native Ruby interpreter can be checked using the command `1/usr/bin/ruby --version`, and the Ruby folder location is typically in `/usr/bin/ruby` or `/usr/local/bin/ruby`. A virtual environment like rbenv or rvm is used to manage different Ruby versions, fetching source code from the internet, compiling it locally, and making it available under a path. The rbenv tool is recommended for its simplicity and ease of use, but other tools like chruby and ruby-install are also available. To install a new Ruby version using rbenv, one can list available versions with `1curl -fsSL https://github.com/rbenv/rbenv-installer/raw/main/bin/rbenv-doctor | zsh`, install a specific version with `1rbenv install 3.1.2`, and set the global configuration with `1rbenv global 3.1.2`. It is also important to consider security vulnerabilities and use tools like Snyk for gem dependency management and code analysis.