In programming terminology, an expression is a statement, or portion of a statement, that results in a single value. An example of an expression is 2+3, which evaluates to 5. When the Explain™ interpreter reaches an expression, the interpreter evaluates the expression term by term to arrive at the expression's value.

Expressions may be combined, e.g.:

A + B * C

A eq B or C eq D

Assignments and tests can be made with combined operations:

D = A + B * C

if (A eq B or C eq D)