A fraction is made up of 2 numbers. The top number is called the NUMERATOR and the bottom number is called the DENOMINATOR. In the fraction the 3 is the numerator and the 4 is the denominator.

DENOMINATOR
This number shows how many equal 'pieces' something has been divided into. In the fraction, the denominator is 4 which means there are 4 equal pieces that make up the whole.

NUMERATOR
This shows how many of those pieces there are. In the fraction there are 3 out of the total of 4 pieces.

Example:
If we cut a pizza into 4 equal slices there will still be 4 pieces on the plate. This will make a fraction of (or 1 whole).

But if we eat one of the pieces 1 out of the 4 pieces is now missing () and there will be 3 of the 4 original pieces left ().

The denominator has stayed the same (4) because the pizza was split into 4 pieces and that hasn't changed but the numerator has changed from 4 when we first cut the pizza to 3 after we had eaten one of the slices.