Fans of Go (called gophers) describe Go as having the expressiveness of dynamic languages like Python or Ruby, with the performance of compiled languages like C or C++.
The language is open source, and was started by engineers at Google. It's written using a C-style syntax, has statically typed variables, manages memory using garbage collection, and is compiled into stand-alone executables.
Go is noted for the concurrent programming features built into the language core, the networking packages in the standard library (such as a web server), fast compilation and execution speed. Its simple, minimalistic and consistent language design make for a delightful experience, while the abundant and thoughtful tooling addresses traditional problems such as consistent formatting and documentation.
The home page for Go is golang.org, and there is an excellent interactive tutorial at tour.golang.org.