2-prong outlets are considered outdated and dangerous due to their lack of grounding. Grounding is how electricity is safely transferred in the case of an unstable current. If an electrical accident such as a short circuit occurs, the dangerous current travels through the ground wire instead of potentially shocking you.
Most new appliances and electronics come with 3-prong plugs designed for 3-prong outlets. If your older house is equipped only with 2-prong receptacles, you’re likely using adapters.
When installed properly, with the metal grounding prong attached to the screw at the center of the outlet plate, the adapters can ground your outlet. But it’s not necessarily safe. A better solution is to hire a professional to replace your receptacles with 3-prong models.
When you buy the replacement receptacles, choose models that include a ground-fault circuit interrupter. This will serve as a sort of “imitation” ground and can greatly eliminate the chance of an electric shock.
It’s a good idea to use GFCI receptacles wherever you replace 2-prong outlets in your house, but it’s especially important in the kitchen, bathroom, laundry room, and garage—anywhere that you use water and electricity in the same room.