app.blade.php exists within a layouts directory
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>@yield('title', 'Laravel')</title>
</head>
<body>
<div class="container">
@yield('content')
</div>
@yield('footer')
</body>
</html>
@extends('layouts.app')
@section('title', 'Laravel | Home')
@section('content')
<h1>Hello World!</h1>
@endsection
@section('footer')
Copyright {{ date('Y') }}
@endsection