Why is it difficult for users to know what to type in these text fields?

<html>
<head><style>body {min-height: 300px;} input { font-size: 16px; } textarea { font-size: 16px; } </style></head>
<body>
  <h3>Log in</h3><input type="text"><input type="text">
</body>
</html>]]>
Because the placeholder attributes are missingBecause the closing tags are missing

Users won't know what to type in because the placeholder attributes aren't set.