How function reputation

How function exatly the reputation ?
When a recieve/sent bad rep the square is sometimes grey,sometimes red.
When a recieve/sent bad rep the square is sometimes grey,sometimes green
I had two bad rep and two good rep and i had -2 points
I have recieve a good ponit and i have still -2 points
I have give someone a good rep ( its the only rep he have) and i have +10 points.
Am i totall dummy or i don't have understang anything o_O ?

I have 2 bad and 5 good rep, total = +2 points...
No i don't understand anything too...

i already saw someone with only 2 good rep, and who have 0 points...
i think there is some bugs with the rep count...

reputation does not have many bugs, its just quite sophesticated. the karma it gives / takes is calculated by the overall importancy of the user who is rating, and that counts in postcount, date joined, reputation, and maybe some other things.

not everyone have rep power, and some have more than most. that's why you can have on bad and 5 good, but still in negative.