How to convert a Go struct to JSON and handle errors?

Hello everyone! I'm a beginner Go developer and I've encountered a problem when converting a struct to JSON. I'm writing a simple service for managing users, and I need to serialize data to JSON for sending via HTTP.\n\nHere's my struct:\n\n```go\ntype User struct {\n Name string\n Age int\n Email string\n}\n```\n\nI'm using `json.Marshal()`:\n\n```go\nuser := User{Name: "Ivan", Age: 30, Email: "ivan@example.com"}\ndata, err := json.Marshal(user)\nif err != nil {\n log.Fatal(err)\n}\nfmt.Println(string(data))\n```\n\nBut the result confuses me — the fields are output with capital letters: `{"Name":"Ivan","Age":30,"Email":"ivan@example.com"}`. In the documentation I saw that you can use tags, but I don't understand how to apply them correctly. Also, what about fields that might be