While Envoy is not a service mesh in itself, it is worth mentioning in this section due to its use in Istio.
Envoy is a service proxy that acts much like Nginx or HAProxy. The main difference is that it can be reconfigured on the fly. This happens programmatically via an API and does not require the configuration file to be changed and the daemon to then be reloaded.
Interesting facts regarding Envoy are its performance and popularity. According to tests performed by SolarWinds, Envoy beats the competition when it comes to performance as a service proxy. This competition includes HAProxy, Nginx, Traefik, and AWS Application Load Balancer. Envoy is much younger than the established leaders in this space, such as Nginx, HAProxy, Apache, and Microsoft IIS, but this didn't stop Envoy from entering the top 10 list of most-used web servers, according to Netcraft.