Surround Sound Receiver What Is The Optical Jack For On My Surround Sound Receiver/TV?

What is the optical jack for on my surround sound receiver/TV? - surround sound receiver

My friend gave me the receiver, all cables and speakers. I have no instructions and could not understand what I do not play around. I recently received a new LCD TV and I realized that on the back of the TV there is an optical connector. It is also a template in the. Would it be a quick way to connect between the TV and receiver? Then I can find a way to connect the DVD player in touch later. Also can anyone tell me what these mean son, and if you decide to, you can find in the business. Thanks