A.C. Alternating current,the "Humm" you hear around energized transformers, 60Hz(cycles)

@Louise1920 I remember learning that Edison (an actual relative) had been promoting DC, which was far more dangerous than AC, and many of those ‘ads’ were to convince people of DC’s danger. Obviously, AC won that campaign

@Varn Yes,I believe Arc, or now called MIG(Metal,inert Gas) and TIG(Tungsten,Inert Gas) uses D.C. for welding(I could be wrong). But there's always something new being created in the welding process.

@Varn I don't know that DC is any more or less dangerous than AC, but it is easier to send electricity long distances and distribute it to customers with AC.

Some of the very long distance lines are DC, but it is unusual.

@GeorgeRocheleau Yes,but then run through a converter getting A.C. back for industrial or commercial use. D.C. does not transmit as well as A.C.,it needs booster stations every so many miles.