Here we will discuss the following basic tags. 

• Highlight <mark>
• Deleted <del>
• Strike <s>
• Inserted <ins>
• Underline <u>
• Subscripted <sub>
• Superscripted <sup>

Highlight <mark>

This <mark> element gives highlighted effect to the text. It is a paired tag. 

Deleted <del>

This <del> element gives strike through the text and produces an impression similar to cancelled text. It is a paired tag.

Strike <s>

This <s> element gives strike through the text and produces an impression similar to cancelled text. It is a paired tag.
Main difference between s and del is del shows removal from document and s shows information is no longer accurate.

Inserted <ins>

This <ins> element represent insert function, it gives Inserted impression to the text. It is a paired tag.

Underline <u>

This <u> element represent insert function, it gives Underline impression to the text. It is a paired tag.

By the HTML 4.01 specification, u means underlined text style, whereas ins means that its content has been "inserted [...] with respect to a different version of a document"

Subscripted <sub>

This HTML element <sub> give selected text effect of subscripted, it will look like text slightly vertically down to co-related text.  For example H₂O, Sample₁ etc

Superscripted <sup>

This superscripted element helps in representing selected text vertically upper to the correlated text. 

For example  Reference ^[1],x² + y² = z² etc