Inner and outer tracks

Morning Clan..

Can someone please explain to me the difference and importance of the inner and outa tracks in each venues, like turfontein, kennilworth, scotsville,etc..

I can't believe iv been punting for 5/6 years since I ws 16 and didn't have a clue of the difference.

Like wise how will I find out if this weekends JHB meeting is on the inner or outer as Magiclips says selbourne is superior on the inner course, thus making him great value at 11/2 for Saterdays race