Check out example codes for "differences between html and xhtml". It will help you in understanding the concepts better.

Code Example 1

In HTML, you can do this:
<meta charset="UTF-8"> and <meta charset="UTF-8" />
In XHTML you have to do this:
<meta charset="UTF-8" />
You can also do this in XHTML:
<custom-tag />
but you can't in HTML.

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