What is a Go file?

Go (also called Golang) files contain source code in the Go programming language, created at Google by Robert Griesemer, Rob Pike, and Ken Thompson in 2007, with public release in 2009. Go was designed to address software engineering challenges at Google’s scale: slow build times in large C++ codebases, verbose dependency management, and the difficulty of writing concurrent server software. It prioritizes readability, fast compilation, and a minimal language specification that fits in one short document.

Go compiles to static, self-contained binaries with no runtime dependency — a Go web server ships as a single executable that runs on any Linux server without installing anything else.

How to open Go files

• VS Code (Windows, macOS, Linux) — With the official Go extension (gopls language server)
• GoLand (Windows, macOS, Linux) — JetBrains’ dedicated Go IDE
• Vim/Neovim — With gopls via LSP
• Any text editor — Go files are plain UTF-8 text

Technical specifications

Common use cases

• Cloud infrastructure: Docker (containerd), Kubernetes, Terraform, Prometheus are all written in Go
• Web services: REST APIs and gRPC microservices (frameworks: Gin, Echo, Chi, Fiber)
• CLI tools: Fast, single-binary tools (e.g., gh, hugo, k9s, fzf)
• DevOps tooling: CI/CD systems, infrastructure automation, cloud CLIs (AWS, GCP, Azure all have Go CLIs)
• Networking: High-performance proxies, load balancers (Caddy, Traefik)

Go code example

package main

import (
    "encoding/json"
    "net/http"
)

type Response struct {
    Message string `json:"message"`
    Status  int    `json:"status"`
}

func handler(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(Response{
        Message: "Hello from Go",
        Status:  200,
    })
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

This is a complete, runnable HTTP server. Go’s standard library includes production-quality HTTP, JSON, crypto, and networking packages with no external dependencies required.

Goroutines and concurrency

Go’s concurrency model uses goroutines (lightweight threads managed by the Go runtime) and channels for communication:

func processItem(id int, results chan<- string) {
    // Simulate work
    results <- fmt.Sprintf("item %d done", id)
}

func main() {
    results := make(chan string, 10)
    for i := 0; i < 10; i++ {
        go processItem(i, results) // launch goroutine
    }
    for i := 0; i < 10; i++ {
        fmt.Println(<-results)
    }
}

The Go runtime multiplexes thousands of goroutines onto a small number of OS threads. A typical Go server can handle tens of thousands of concurrent connections on modest hardware.

Error handling

Go has no exceptions. Errors are regular values returned as the last return value:

file, err := os.Open("data.txt")
if err != nil {
    log.Fatalf("failed to open: %v", err)
}
defer file.Close()

This makes error handling explicit and visible in code. The defer statement runs cleanup code when the function returns, regardless of how it returns.

Go modules

Go modules (introduced in Go 1.11) manage dependencies via go.mod:

go mod init example.com/myapp   # Initialize module
go get github.com/gin-gonic/gin  # Add dependency
go mod tidy                      # Clean unused deps
go build ./...                   # Build all packages
go test ./...                    # Test all packages

The go.sum file records cryptographic hashes of all dependencies for reproducible, tamper-proof builds.