Golang is a fast and modern programming language that helps you build simple, reliable, and efficient software. To build a backend API with GraphQL and Golang, you can use the gqlgen library, which provides a schema-first approach to building GraphQL APIs. This approach allows you to define your data requirements based on the types and operations your clients need, making it easier to focus on what you need first and figure out how to do it later. The gqlgen library generates boilerplate code for queries and mutations based on the schema file, making it easy to develop using a schema-first approach. By defining your schema before writing code, you can quickly adapt to changing business requirements and avoid wasting time writing unused queries or template code.