• HTML makes no attempt to display mathematics correctly
• Separate markup language, MathML
• Superscripts and subscripts are provided
• Similar to vertical-align:sub and vertical-align:sup

<p>x_i = y_i + 2^{a + b²}</p>

This would be displayed as: x_i = y_i + 2^{a + b2}

By customised styling: x_i = y_i + 2^{a + b2}

sup {font-size:14pt}
sup sup {font-size:10pt;padding:2pt}
sup sup sup {font-size:8pt;padding:1pt}

For some browsers, the two lines of mathematics above may be significantly different