Common Types of Touch Technology 
A variety of touch technologies are in use today. Each touch technology actual refers to a touch "sensor" type, so when you hear the terms "resistive, infra-red, surface capacitive, optical, surface acoustic wave," etc., we are actually refering to "resistive sensor, infra-red sensor, surface capacitive sensor, optical sensor, surface acoustic wave sensor," touch technology. Discover more here.
Understanding Construction: How Construction Method Influences Touch Technology Use
Each type of sensor technology has a method of construction, which is the method in which the touch sensor is applied to the display.
For example, optical and infra-red require a mechanical frame added to the original display to construct the touch display. This is often referred to as frame-based construction.
Surface capacitive, surface acoustic wave and 3M's Dispersive Signal Technology (bending wave) are constructed using on-glass construction, in essence placing the actual touch sensor across the exisiting LCD display and encosing it with the original display manufacturer's bezel. This can produce a display with seamless design, preserving the orginal display's appearance, function and of course the manufacturer's brand equity. Read more about on-glass and frame-based construction here. Discover more here.