Rack
Rack is a modular web server interface for Ruby that provides a minimal, standardized API for connecting web servers and Ruby web frameworks. It sits between the web server and the Ruby application, handling HTTP requests and responses by converting them into a simple, uniform format. This abstraction allows developers to write web applications that are server-agnostic and easily composable with middleware.
Developers should learn Rack when building Ruby web applications, as it is the foundation for most Ruby web frameworks like Ruby on Rails and Sinatra, enabling interoperability and middleware integration. It is essential for creating custom middleware, testing web applications in isolation, or developing lightweight web services without a full framework. Use cases include building APIs, adding authentication layers, or optimizing request/response handling in Ruby-based projects.