Go is an open source programming language that makes it easy to build simple, reliable, and efficient software. - Golang.org
Go is best described as "C" for 21st century. Go was developed in 2007 by Robert Griesemer, Rob Pike, and Ken Thompson at Google and open sourced in 2009. Go is general purpose programming language that can be at various places.
Go has no implicit numeric conversions, no constructors or destructors, no operator overloading, no default parameter values, no inheritance, no generics, no exceptions, no macros, no function annotations, and no thread-local storage. - The Go Programming Language by Brian W. Kernighan, Alan A. A. Donovan
Go is created to bridge gap between safety and performance. Languages like C, C++ are very performant, but at the same time, they are not safe. On other hand languages like Ruby, Python are safer, but are slower. Go sits at a sweet spot where, Go is fast enough to build platforms, at the same time provides safety like Ruby, Python.
In a nutshell, we wanted a language with the safety and performance of statically compiled languages such as C++ and Java, but the lightness and fun of dynamically typed interpreted languages such as Python - Rob Pike