Go is an essential programming language used by Raintank in various projects, including powering Grafana's backend and handling metric processing in the raintank-metric worker. Its efficiency, ease of deployment, and cross-platform compatibility make it a preferred choice for backend and systems programming. Go's strengths include its speed, concurrency features, and profiling tools, though it has downsides such as a frustrating build system and lack of default dependency versioning. Despite these challenges, Go has continued to evolve, with improvements in garbage collection and tooling, making it a powerful and accessible language.