Gin .tmpl and .html for template,What's the difference?

.tmpl and .html for template,What's the difference?

func main() { router := gin.Default() router.LoadHTMLGlob("templates/") //router.LoadHTMLFiles("templates/template1.html", "templates/template2.html") router.GET("/index", func(c gin.Context) { c.HTML(http.StatusOK, "index.tmpl", gin.H{ "title": "Main website", }) }) router.Run(":8080") }