It is important for many people to know the difference between a grounded conductor vs. an ungrounded conductor. As an electrician, I see that people just have this tendency to hook wires up without a lot thought of how the wires should connect. People often think if it works, then it works. However, they do not understand what can happen if the wires do not work because of the way people decide to connect them.
The purpose of grounded conductor is to prevent people from getting dangerous electrical stocks when using electrical appliances. You will most often see grounded conductors in electrical outlets. Certain wires must be present and connected correctly to prevent an electrical shock in case a wire comes loose and touches the metal outlet. If the outlet is ungrounded and a wire comes loose and is hot, then it can cause a shock. If the wire touches anything metal, the metal becomes hot and can shock someone. Grounding prevents the metal from becoming hot and shocking someone.
Three-pronged outlets are designed to guard against dangerous electrical shock because they should have grounded conductors. However, the mistake many people make in older homes is replacing a two-pronged outlet with a three-pronged outlet and forgetting to change the wiring. This is actually illegal in some states because the three-pronged outlets provide an illusion safety, when in fact this is very dangerous. If you are unsure if your outlets have been properly grounded, then think about calling an electrician to check it out, especially in an older home. Any three-pronged adapters you buy will also have the same problem because the wiring has not been changed.
The only way to safely convert an ungrounded conductor to a grounded conductor in outlets is to change both the wiring and the outlets. This is something an electrician can help with. You do not have to convert the entire house at one time. If there are certain areas that you tend to use more than others, then have an electrician rewire and replace those outlets first. Overtime all of your outlets should eventually have grounded conductors in all your rooms with outlets.
The difference between having a grounded conductor vs. ungrounded conductor can make a huge impact on the safety of your home. Having an electrician look at your outlets to make sure all the wiring is correct will give you peace of mind.