search information about diodes
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Are you thinking of the commonly used practice of drawing the equivalent circuit of a transistor as two back-to-back diodes with the base as the common connection point?

 

Are you referring to the diode often shown in drawings of MOSFT transistors?

 

Hello,

The schematic is unreadable.
Please repost it with a white background.

Bertus

 

It looks like the collector of an NPN is conected to a relay coil, so I would think maybe to prevent inductive kick back, from flowing back into the transistor, this diode will bypass the inductive spike around the transistor to ground.

Usualy a diode is put across the relay coil itself, to prevent this.

 

I agree that the negative schematic can barely be seen, even when I make a negative of it. It has lines all over the place.

The diode across the collector and emitter of the transistor does nothing and can be removed. The diode across the relay coil arrests its high voltage spike.

 

You can put a zener across the collector and emitter to eat spikes too. Some ECU's do this with their fuel injector drivers.