sum (LaTeX symbol)

In LaTeX, \sum is rendered as $\sum$ inside math mode. The difference between the summation operator \sum and \Sigma, which generates the capital letter $\Sigma$, is that \sum appears larger, and that it supports the limits to be displayed below and above the symbol.

The following example illustrates the difference between \sum and \Sigma.

Markup	\sum_{n=1}^\infty\frac{1}{2^n}=1
Renders as	$\sum_{n=1}^\infty\frac{1}{2^n}=1$

Markup	\Sigma_{n=1}^\infty\frac{1}{2^n}=1
Renders as	$\Sigma_{n=1}^\infty\frac{1}{2^n}=1$