Along with the Reactive Manifesto, we also have a standard specification on Reactive Streams. Everything in the reactive world is accomplished with the help of Reactive Streams. In 2013, Netflix, Pivotal, and Lightbend (previously known as Typesafe) felt a need for a standards specification for Reactive Streams as the reactive programming was beginning to spread and more frameworks for reactive programming were starting to emerge, so they started the initiative that resulted in Reactive Streams standard specification, which is now getting implemented across various frameworks and platforms.

You can take a look at the Reactive Streams standard specification at—http://www.reactive-streams.org/.