Questions on fractions, i.e. expressions (not values) of the form $\frac ab$, including arithmetic with fractions. Not to be confused with the tag (rational-numbers): fractions denote rational numbers, but the same rational number may be written in different ways as a fraction.
A fraction is simply an expression $\frac{a}{b}$, where $a$ and $b$ are typically integers (where $b\neq 0$). This tag may be used, when $a$ and $b$ are more general expressions or algebraic objects; however, consider adding a more specific tag also:
rational-functions for fractions of two polynomials
algebra-precalculus for basic questions about a function or expression which is written as a fraction
continued-fractions for continued (infinitely nested) fractions
abstract-algebra for a fraction taken in some group, ring, or field
localization, ring-theory, integral-domain, and/or commutative-algebra for the field of fractions of a ring.
Fractions are distinct from rational numbers because they are a representation: $\frac 34$ and $\frac{30}{40}$ are different fractions that happen to represent the same rational number.
For arithmetic with fractions, this tag is appropriate along with arithmetic.