As mentioned in the overview, there are four basic types of power conversion. Once you have determined the type of converter that you need, you will need to consider the other options: specifically, filtered vs. unfiltered, and regulated vs. unregulated.
Filtered indicates that the converter is designed to prevent line noise from being carried into the connected device. This is important for audio and video equipment, as line noise can cause interference issues, such as static or a poor picture.
Regulated means that the converter is designed to provide a specific level of unvarying power. This is required for devices which are not tolerant of minor power changes and/or which state that they require a regulated power supply.
The chart below lists the various situations in which you would need a power converter and which converter should be used.
Note: United States voltage is 110/120V AC.