A __case fraction__ is a fraction symbol that is typeset as a single character.

½

This is a __stack fraction__. Also called a __horizontal bar fraction__ or a __vertical fraction__.

$\frac{1}{2}$

This is an __built fraction__ or __built-up fraction__. It uses at least 2 blocks of type. Also called an __on-line fraction__, because both numbers sit on the baseline.

The numerator and denominator are regular numerals separated by a forwardslash.

1/2

The term __case__ may refer to the physical case in which the typesetting blocks were stored.