how to put a box around text using html css code example

Example 1: how do i make a boxin html

<div style="width:500px;height:100px;border:1px solid #000;">This is a rectangle!</div>

Example 2: how to add a border around text in html

<p style="border:3px; border-style:solid; border-color:#FF0000; padding: 1em;">
  First example with text surrounded by a red border.<br>This example also has multiple lines.
</p>