Antenna average gain vs peak gain

Hi,

I would like to understand what is the difference between an antenna average gain and peak gain I can see in the following datasheet:

http://taoglas.com/images/product_im...s/PCS.07.A.pdf


Thanks

The peak gain is the point in 3D space where the antenna gain has maximum value, while the average gain is averaging all the points in that 3D space.