How to combine a few lists?

Question

There are two lists: a={12,23,4,5,7}, b={11,3,24,5}

I would like to combine them like this: ab={12,11,23,3,4,24,5,5,7}

How it can be done?

ClearAll["Global`*"]
a={12,23,4,5,7};
b={11,3,24,5};

Answer 1

One way out of many could be

Riffle[a, b]