Sound cards are actual audio cards that you'd slide into a computer, or they can be external. In my case, I have an external sound card, which I'll show. And basically, it plugs in through a USB interface, but typical sound cards plug into the PCI slot on a motherboard of a standard computer. Also, most laptops like I have here have integrated sound cards that plug in either on the front or on the side. These sound cards are just generally what literally, the computer uses to reproduce sound. Sound cards are generally not built into desktops. They are actual cards themselves, unless you're looking at a low-end PC. On all laptops they will have some sort of sound card built in always. Whether that sound card has a microphone, or line-in, or specific connections is up to the manufacturer. Generally, the more higher end sound cards will have better connectors and digital infa interfaces. On my particular computer I have headphones, line-in, and microphone slots, as well as HDMI which supports audio as well. But for me, what I use; particularly because I don't want to pack up my speakers every time I move is I have an external sound card that my speakers, stationary speakers stay plugged into, and it's plugged in through a USB. So, when I sit down at my desk after taking my laptop away I just plug in a one USB cable and all my sound works, my all the other peripherals that are plugged up to that USB cable will start working automatically. This external sound card is made by Phillips. It's been through a lot of bangs as you can see, but basically, on the front here there are some buttons here. The buttons are just for, buttons are just for looks, so a lot; actually, all of these functions that are on the sound card itself are actually controlled through Windows. So, if you say mute it'll actually mute here and show it here, but the actual software is what controls it; not these actual hardware buttons. On the back here you'll see all the different connectors that this particular sound card provides. I bought this sound card particularly for digital output here, so we have digital output here, the coax and optical, and then the standard connections which are green, which is for stereo left and right. Then you have the the digital line-in, or or excuse me, that's the center, the center channel, so that's for surround sound. And then you have the rear connectors, so this would be rear left and right, and the green is always front left and right, or if you just have green by itself it's left and right. And then you have line-in. This is if you had like an iPod or something that you wanted to feed in directly into it. And then the USB connector. How it connects to my laptop.