AD/DA conversion = The conversion of analog audio (and live sound) into digital signals and vice versa.

Adat optical = And optical digital signal originally used to transport eight channels of digital audio from an Adat multitrack recorder.

Analog input = The ability to record actual sound coming from a microphone or other source and translate it into digital data for use in your computer.

Bit depth = A byte contains bits of data. Each bit is expressed as a 0 or 1. Bit depth refers to the number of bits per byte. For example, a byte of data at an 8 bit depth could be something like this: 00101110. The higher the bit depth, the greater the detail and precision of the data. CDs are recorded at a bit depth of 16 bits, while it is common for professional audio equipment to handle 24 bits or more.

Digital input = The ability to record digital signals directly from digital devices such as digital multitrack recorders, mixers and so forth.

DSP effects = Some sound cards have their own built-in effects processors. DSP stands for digital signal processing.

I/O = Inputs and outputs. The more, the merrier, as you can send out more channels to an external mixer as well as record more channels simultaneously.

Latency = A delay between the input and the output of the sound card. For example, you play a sound on the keyboard and do not hear it until a moment later.

MIDI interface = And input for MIDI signals coming from a MIDI sequencer or keyboard. MIDI is not actual sounds, it is a set of digital instructions to a synthesizer or sound bank.

Optical connection = Optical digital signals use a special cable which is thinner than most cables. They have a unique interface as well. Adat signals can carry up to eight channels of audio on them. Other optical signals carry stereo channels.

PCI = A type of card. The PCI sound card is installed into the computer itself in a PCI slot. External sound cards may connect via a USB port.

Sample rate = The amount of audio samples per second. Similar to a old-style film, and audio track consists of lots of little snapshots, called frames. The human ear perceives them as being one continuous track. The higher the sampling rate, the smoother and more realistic the audio. Additionally, since waves of audio get longer at lower frequencies, smaller sampling rates do not always captured the entire frequency range at that lower end. CDs use a sample rate of 44.1 kHz, while most professional recording equipment can achieve sample rates of 96 kHz.

Soft synth = Short for software synthesizer. A bank of sounds that can be played by a MIDI sequencer. Many sound cards have a soft synth on board. You simply route the MIDI output to the sound card's soft synth and you will hear it play from the sound card's output.

SPDIF = A type of digital signal develop by the Sony Corporation. It comes in both electronic and optical varieties.