The document discusses the rise of functional programming. It provides an example comparing an imperative solution in Java to sum the ages of persons over 20 to a functional solution. The functional solution uses reduction and has no mutable state. Functional programming is described as writing what you want, not how to do it, with everything being a function. Benefits mentioned include stateless programming which aids reasoning, easy distribution and parallelism, and easier program proof. The document also briefly mentions functional languages like Haskell and Erlang, as well as Java's addition of lambda expressions in Java 8 to provide more functional capabilities.