The standard for major electrical appliances since 1969 is to have three-pronged plugs. Soon after this standard was introduced, the household outlets started to change over to three-prongs. A three-pronged outlet is a grounded outlet. The third prong, the one below the “hot” and “neutral” slots, is the “ground.” The ground slot is there to protect a person from receiving an electrical shock from the metal casing of an appliance because the electricity from the hot wire side is sent into the ground in case there is excess. You’ll notice that some appliances still use two-prong plugs because they don’t have large metal cases in them that can create this problem.
This lengthy explanation about grounded outlets and three-pronged plugs is necessary to get to the big question, “Is it okay to use a three-pronged adapter?” The cheater plugs allow you to plug a three-pronged plug into a two-pronged outlet, which you wouldn’t be able to do otherwise. If you live in an older home with two-pronged outlets, you may have plenty of these cheater plugs around. Is this a good idea?