Answer:

A fraction is part of a whole.

For example, the given circle below has been split into 5 equal parts. Each is called a fifth, written
1 / 5. The fraction of the whole circle which has been crossed is:
The number of crosed parts / The number of parts together = 1 / 5 (one fifths)

The top number of a fraction is called the numerator and the bottom number is called denominator.