Vert.x is a toolkit for building reactive applications on the Java Virtual Machine (JVM). It is used to build microservices at an educational publishing company in the Netherlands called Malmberg. Vert.x applications are event-driven, non-blocking, and distributed using an event bus. The presentation discusses why Vert.x was chosen, provides demos of basic and advanced Vert.x features, and explains how Vert.x supports building microservices with characteristics like independence and lightweight communication. Real-world experiences developing with Vert.x for five years are also shared.