A service mesh is an additional infrastructure layer that provides a means of communication between all services in a given application. It is typically deployed as a series of proxies alongside each service instance. Since the service mesh proxies are deployed alongside the application services and not as part of it, they are often referred to as sidecars. This means that as a whole, these sidecar proxies are a mesh network and an infrastructure layer separate from the application. A service mesh not only brokers communication between all services in an application but, since all requests, both internal and external, pass through it, it provides a means for handling many tasks that can be obfuscated away from the application.
Istio is an open-source service mesh that makes it easier for a team to create a network or server cluster of deployed services. Istio provides several vital services consistently across a mesh network such as: