Parallel....series....

What are you doing, Doug?

Series think "in line" like flashlight batteries in a flashlight, voltage adds the total of the individual. Neg to pos.................neg to pos...........neg to pos........

Parallel, "side by side" you could parallel 2, 20, or 200 million D cells and the output voltage will still be 1.5V nominal.........neg to neg...........pos to pos

Jumpering a vehicle battery is parallel.......more amps, same voltage