If you would like to perform an action by energising to act ( Logic 1 = desired output) then it's positive logic.

If you would like to perform an action by de-energising to act ( Logic 0 = desired output) then it's negative logic.

Here is an example for the positive and negative logic

POSITIVE LOGIC NEGATIVE LOGIC

o/p Y = 1 (energise to act) o/p Y = 0 (de-energise to act)

A B Y A B Y

1 1 1 1 1 0

1 0 0 1 0 1

0 1 0 0 1 1

0 0 0 0 0 1

any how the required action can be performed by using either a positive logic or a negative logic.