# Math Insight

### Variable definition

A variable is a quantity that may change within the context of a mathematical problem or experiment. Typically, we use a single letter to represent a variable. The letters $x$, $y$, and $z$ are common generic symbols used for variables. Sometimes, we will choose a letter that reminds us of the quantity it represents, such as $t$ for time, $v$ for voltage, or $b$ for bacteria.