ReasonML, developed by Facebook in 2017, is a programming language designed to provide a faster and simpler alternative to JavaScript, while maintaining familiarity for JavaScript programmers by being built 80% on top of OCaml. Despite its small community, ReasonML offers notable advantages such as an excellent type system and a practical approach to immutability, enhancing performance and reliability in programming. The language compiles to JavaScript, producing readable code that supports interoperability with JavaScript libraries, which is facilitated through the use of the "raw" keyword and other interop features like BuckleScript. ReasonML's connection to OCaml brings expressiveness and safety, with the latter ensuring many runtime errors are caught during compilation, thus improving efficiency. ReasonReact combines React's component-based approach with ReasonML's strengths, addressing some inconsistencies between React and JavaScript by leveraging a static strong type system and functional programming paradigm. The synergy between ReasonML and JavaScript, highlighted through interop and Foreign Function Interface (FFI), allows developers to combine the strengths of both languages for more powerful web applications.