What is the Reactive Manifesto?

I am starting to read "ASP.NET Core 2 and Angular 5" by Valerio De Sanctis which just arrived on my doorstep today. I have only read the first page. The first page namedrops The Reactive Manifesto which is the first new thing I have learned. This is a high level spec for what progressive web apps should be. They should be:

1. Responsive
2. Resilient, i.e. replication, containment, isolation, delegation
3. Elastic (sharding and load-balancing and the like / resources managed well)
4. Message Driven