Definition:Field of Rational Numbers

Definition
The field of rational numbers $\struct {\Q, + \times, \le}$ is the set of rational numbers under the two operations of addition and multiplication, with an ordering $\le$ compatible with the ring structure of $\Q$.

When the ordering $\le$ is subordinate or irrelevant in the context in which it is used, $\struct {\Q, +, \times}$ is usually seen.

Also see

 * Rational Numbers form Ordered Field

Thus:
 * $\struct {\Q, +}$ is the additive group of rational numbers
 * $\struct {\Q_{\ne 0}, \times}$ is the multiplicative group of rational numbers
 * The zero of $\struct {\Q, +, \times}$ is $0$
 * The unity of $\struct {\Q, +, \times}$ is $1$.