GI Help

can someone please explain to me what GI is and what it does for you? The only thing i think I know is that it stands for Gylcemic index?(not sure thought)

Glycemic index of a particular carbohydrate refers to its influence on your blood glucose/insulin levels. The higher a food is ranked on the index the more drastic of a change it can produce on your blood sugar levels. Typically you would want to eat High GI foods post workout because they digest quickly. Foods like whole wheat have less of an effect on blood sugar levels and the flux of insulin because they are digested more slowly.

http://www.glycemicindex.com/

does it matter if you have foods w/ a high GI for lunch or dinner or breakfast if your mass gaining, or is just better to keep them for after workouts?

dint i explain this to you yet rich dog. Ask me in person noob

High glycemic carbs have 2 uses in a day, to break a fast, and to reload after a workout.  They are really not needed any other times of the day.