Speakers fall into one of two categories, Active or Passive.

Active speakers (Also known as Amplified Speakers) are used mostly for desktop computers. They have a built-in amplifier and are fed by a low-level signal passed along an interconnect cable originating at your preamplifier or controller. Because the amplifier is an active electronic device, it needs power, so you have to plug them into a power outlet.

Alternatively, a passive speaker is a speaker which does not have its own power source and draws power from a separate amplifier. Because of this, Passive speakers require longer lengths of cable, which works out well if you have amplifiers that can run multiple speakers.

Multichannel audio allows for outstanding the sound reproduction quality, The three-dimensional sphere of human hearing can be virtually achieved with audio channels above and below the listener. To that end, the multichannel surround sound application encircles the audience (left-surround, right-surround, back-surround), as opposed to "screen channels" (center, [front] left, and [front] right), i.e. ca. 360° horizontal plane, 2D). Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small plastic boxes with mediocre sound quality. Some of the slightly better computer speakers have equalization features such as bass and treble controls, improving their sound quality somewhat. The internal amplifiers require an external power source. More sophisticated computer speakers may have a subwoofer unit, to enhance bass output, and these units usually include the power amplifiers both for the bass speaker, and the small 'satellite' speakers. Laptops & Notebooks come with integrated speakers. Unfortunately the tight restriction on space inevitable in laptops means these speakers unavoidably produce low-quality sound.

2.0-Channel Speaker System: A pair of matched speakers producing Stereo Sound.

2.1-Channel Speaker System: A pair of matched speakers producing Stereo Sound, Plus a Subwoofer for detailed Bass Tones.

4.0-Channel Speaker System: A five speaker system producing surround sound that extracts four audio channels from a specially encoded two-channel source: Two channels for speakers at the front-left (L) and right (R). One channel for speaker at the center-center (C). One channel for both surround speakers at the rear mono surround channel (S).

5.1 Channel Speaker System Analog: Also called Surround Sound. Five Speakers and Subwoofer described as follows:: Two channels for speakers at the front-left (L) and right (R). One channel for speaker at the center Two channels for surround speakers at the rear surround left and surround right One low-frequency effects channel (LFE).

5.1 Channel Speaker System Digital: 6 Channel Sound Card is Needed. Delivers Five discrete audio channels and 1 LFE channel from a 6 channel source: Two channels for speakers at the front left (L) and right (R). One channel for speaker at the center (C). Two channels for surround speakers at the rear surround left (LS) and surround right (RS). One low-frequency effects channel (LFE). Describes the Dolby Digital, Digital Theater System (DTS), and Sony Dynamic Digital Sound (SDDS) systems. Source media, usually DVD and sometimes Laser Disc or satellite/digital cable is often branded with "Dolby Digital" and/or DTS logos. DTS uses a higher data rate than Dolby Digital, so DTS can achieve higher fidelity. 5.1 surround sound may also be referred to as 3-2 stereo. This defines the configuration that has been standardized for numerous surround sound applications. The term 3-2 refers to 3 front speakers and 2 rear speakers.