<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Select a color</title>
</head>
<body>
<form action="/" method="POST">
<p>Select one or more colors</p>
<label for="red">Red</label>
<!-- name can be "colors" too -->
<input type="checkbox" name="colors[]" value="red" id="red">
<label for="green">Green</label>
<input type="checkbox" name="colors[]" value="green" id="green">
<label for="blue">Blue</label>
<input type="checkbox" name="colors[]" value="blue" id="blue">
<input type="submit">
</form>
</body>
</html>