Ruby

A dynamic, open source programming language with a focus on simplicity and productivity. It has an elegant syntax that is natural to read and easy to write.

Ruby is the language built for programmer happiness: expressive syntax, everything-is-an-object purity, blocks as first-class citizens, and a standard library designed for reading pleasure. Rails carried it to prominence, and the language remains the heart of a productive, opinionated web tradition.

Why founders use it: Ruby optimizes the scarcest resource, developer time, and the community's taste, convention, testing culture, developer-experience tooling, produced an ecosystem where common tasks have beautiful answers. Scripts, scrapers and internal tools get written quickly, and the language's readability makes them maintainable by whoever inherits them.

A realistic use: a Rails product as the main artifact, Ruby scripts for operations, Sidekiq jobs doing the async work, and gems from a mature ecosystem for everything else. Ractors and YJIT keep the runtime improving underneath.

Trade-offs: raw CPU-bound performance trails compiled languages, deployment once meant interpreter wrangling though modern tooling hides it, and the hiring pool is smaller than the mainstream. Compare with Python for data adjacency, PHP for hosting ubiquity, and Elixir for the functional-actor direction Rubyists often admire.