Check out example codes for "how to highlight text in html". It will help you in understanding the concepts better.

Code Example 1

For HTML5: (with 'mark' tag)

<p>Do not forget to buy <mark>milk</mark> today.</p> 

In CSS file: (To customize highlight)

mark {
  background-color: yellow;
  color: black;
}

Code Example 2

<mark>text</mark>

Code Example 3

<body>
<p>The Math test is on <mark>Friday</mark>.</p>
</body>

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