Summary:

- Ruby 4.0 is a major upgrade to the popular programming language, focusing on improving isolation, parallelism, and long-term performance.
- The new version introduces a new virtual machine called Ractor, which allows for parallel execution of Ruby code, enabling better utilization of modern hardware.
- Ruby 4.0 also includes improvements to the language's garbage collector, making it more efficient and reducing memory usage, which is crucial for long-running applications.