Definition:Limit of Mapping

Real and Complex Numbers
As:
 * The real number line $\R$ under the usual (Euclidean) metric forms a metric space
 * The complex plane $\C$ under the usual metric forms a metric space

the definition holds for sequences in $\R$ and $\C$.

However, see the definition of the limit of a real function below:

Limit of Real Function
The concept of the limit of a real function has been around for a lot longer than that on a general metric space.

Also see

 * Definition:Limit of Sequence
 * Definition:Continuity