Some think that "A Speaker is a Speaker" and you only pay for the name. This however is not true. The speaker market is very competitive and you typically pay for the quality first, and maybe brand 2nd. So, finding a good quality speaker that fits into your budget is the most important part.

Speaker Type (Style):

The first thing you need to decide is what type or style of speaker you want. Floor mounted or bookshelf, in-wall or in-ceiling speakers. Ceiling and wall mounted speakers are becomming more popular, and require a little more planning in advance.

Speaker Terms to Look for:

Bipole
A speaker design that generates equal amounts of sound both forward and backward, with the two sounds being "in phase." See also Dipole.

Coloration
Any change in the character of a sound that reduces accuracy, such as an over- or under-emphasis of certain frequencies.

Connectors (pins, plugs, etc.) (Click for pictures)
There are several different ways to connect the cables from your receiver or amplifier to your speakers. Bare wire connections are acceptable, especially with "spring clip" terminals. However, there are other connector types that provide more solid and secure connections, especially with binding post terminals.

Spade connectors are compatible with most binding post terminals. A spade fits around the terminal's central threaded post, allowing you to then tighten the collar down on the spade for a snug, secure connection. But keep in mind, some electronics now have terminals that prohibit the use of spade connectors.
Pin-type connectors will work with both spring clip and binding post terminals. This is probably the best type for connecting a thick, heavy-gauge wire to a small spring clip connector. On a 5-way binding post, this slender pin will also fit the hole that's back near the base of the central post (see binding post illustration, below). You can then tighten the collar down against it.
Banana plugs will plug straight into the center of 5-way binding posts. They make a quick and convenient connection — nothing to loosen or tighten.
Double-banana plugs are the same as banana plugs, except the positive and negative banana connectors are both fixed in a molded housing that spaces them 3/4" apart. (These are even quicker and easier to connect than regular, single banana plugs — as long as the terminals on your speakers and/or receiver are true 5-way binding posts with the proper spacing.)

Crossover
A circuit that divides the frequency spectrum into two or more parts. A crossover acts as a filter, allowing certain frequencies to pass through to the speaker while blocking others. It's the crossover's job to send only high frequencies to the tweeter and only low frequencies to the woofer. (And midrange frequencies to the midrange driver in a 3-way speaker.)

A high-pass crossover allows only frequencies above the "crossover frequency" to pass through, while a low-pass crossover (common in powered subwoofers) allows only frequencies below the crossover frequency to pass through. A "bandpass" crossover combines a high-pass and a low-pass so that the driver (often a midrange unit) only sees a restricted band of middle frequencies.

Decibel (dB)
The standard unit of measure for expressing relative power or amplitude differences. With speakers, it's a measure of loudness. One dB is the smallest change in loudness most people can detect. A 1 dB difference is barely noticeable, but a 10 dB difference is big — a speaker playing at 10 dB higher volume will sound twice as loud.

Another amazing dB fact: for any given set of speakers, each 3 dB increase in volume level requires a doubling of the amplifier power.

Diaphragm
The part of a speaker driver that moves, producing the sound. Each diaphragm is directly connected to a voice coil. The diaphragm for a woofer is a cone, while for a tweeter, it's often a dome.

Diffusion
The scattering of sound. Diffusion reduces the ability of a listener to pinpoint the actual location of a speaker, a useful quality in surround speakers. Diffuse surrounds create a wraparound soundfield that draws you into the on-screen action.

Dipole
A speaker design that generates equal amounts of sound both forward and backward, with the two sounds being "out of phase." Dipoles are often used as surround speakers. See also Bipole.

Direct and reflected sound
The sound that you hear from your listening/viewing position is a combination of the direct sound that travels straight from your speakers to your ears, and the indirect, reflected sound — the sound from your speakers that bounces off the walls, floor, ceiling or furniture before it reaches your ears.

Dispersion
The degree to which a speaker's sound is spread over the listening area.

Driver
Any individual diaphragm (cone, dome, etc.) within a speaker that compresses and rarefies the air to create sound waves, such as a woofer, tweeter, midrange, etc.

Dynamic range
The difference between loud and soft sounds. A speaker with wide dynamic range — one that can reproduce the sudden and wide changes between loud and soft sounds in music and video soundtracks — will sound more realistic.

Efficiency (Sensitivity)
Although a speaker's efficiency rating is almost always correlated to its sensitivity rating, it is actually a different measurement. The efficiency rating for a speaker is a measure of how well a speaker converts watts of electrical power into watts of acoustical power. Most speakers have a very low efficiency rating — between 1% and 10% — so manufacturers rarely provide this information, choosing instead to list sensitivity ratings.

Flat
When a speaker's response is described as "flat," that's a good thing. It means that the speaker can accurately reproduce a signal that is fed to it without adding unnatural coloration to the sound. Specific frequencies don't sound too loud or too soft.

Frequency response
The human ear responds to frequencies from approximately 20 to 20,000 cycles-per-second, or Hertz. A speaker's frequency response indicates how much of that range can be reproduced.

Hertz (Hz)
The unit of sound frequency; one Hz is equal to one cycle per second. The range of human hearing is 20-20,000 Hz. Points of reference: low "E" on a bass guitar is 41 Hz; middle "C" on a piano is 262 Hz; cymbals can go out to 15,000 Hz.

Imaging
The ability of a speaker to reproduce spatial information in a recording so that you can visualize the relative positioning of individual voices and instruments as you're listening.

Impedance
The load value (in ohms) that the speakers present to the amplifier — the amount of resistance to the flow of current. While playing music, a speaker's actual impedance constantly fluctuates; however, speakers are usually given a single nominal impedance rating for easy comparison. Low-impedance speakers (4 ohms or less) can cause problems with receivers or amplifiers that are not designed to deliver large amounts of current.

Midrange
The range of frequencies above bass and below treble that our ears are most sensitive to, which includes most vocal and instrumental sounds. Sometimes refers to a driver designed to reproduce these frequencies.

Phase
Refers to the timing relationship of two or more signals or sound waves. It's especially important to be sure that your stereo speakers are playing "in phase." This means that the drivers (cones and domes) of your right and left speakers are moving in and out at the same time.

If your stereo speakers are "out of phase" — that is, with one set of positive and negative leads reversed — you'll hear significantly less bass, and instead of producing a strong center image, the sound tends to stay localized at the speakers. To learn how to be sure your speakers are in phase, check the Home Speakers FAQ).

Phase control
A 2-position switch found on some powered subwoofers that lets you delay the subwoofer's output slightly so that it is in phase with the output from your main speakers.

Power handling
A measure of how much amplifier power, in watts, a speaker can take before it is damaged.

Resonance
When a component or system vibrates more at a certain frequency than at any other frequency. In a speaker system, resonance with the speaker enclosure or any of the components can lead to colorations in the sound.

Satellite speaker
A small speaker with limited bass response that's often designed to be used with a matching subwoofer.

Sensitivity
A sensitivity rating tells you how effectively a speaker converts power (watts) into volume (decibels). The higher the rating, the louder your speakers will play with a given amount of amplifier power. Sensitivity is often measured by driving a speaker with one watt and measuring the loudness in decibels at one meter.

Subwoofer
A speaker specially designed to reproduce a range of very low frequencies only (the bass). The typical range for a subwoofer is about 20-200 Hz.

A "powered subwoofer" includes a built-in amplifier to drive the speaker.

Surround speakers
In a home theater system, the speakers located beside or behind the listening/viewing position. These speakers can be mounted on the walls, placed on stands, or set on bookshelves. They help create an enveloping three-dimensional soundstage by reproducing the surround information on video soundtracks and music recordings encoded with surround sound. Depending on the format, the surround speakers will be asked to do different things. For details, check out our nuts and bolts discussion of the different surround sound formats.

Terminals
You probably don't think about the connectors on the back of your speakers until you go to hook them up. There are two basic types: spring clips and binding posts.

Spring clip terminals are usually found on lower-priced speakers, and low- to medium-priced receivers. They work best with bare wire connections with small-gauge speaker wire, or pin-type connectors (see connectors, above).
Binding post terminals are a sturdier, more versatile type of speaker jack, often found on higher-quality speakers and receivers, and on most amplifiers. They're threaded, so you can tighten them down against the wire or connector for an extra-snug connection.

Tweeter
A small, lightweight driver that reproduces the highest musical frequencies, like violins, cymbals, female vocals, etc. The typical range for a tweeter is everything above 2,000 Hz or so.

Video shielding
A way of containing a speaker's magnetic energy inside its enclosure. This is usually achieved by placing another speaker magnet back-to-back with the existing one so that the two magnetic fields cancel each other. Shielding may also be achieved by lining the inside of the speaker cabinet with metal.

Voice coil
The cylindrical coil of wire that moves in the magnetic field of a dynamic driver. The voice coil is bonded to the diaphragm, which actually produces the sound.

Woofer
A type of driver that features a cone-shaped diaphragm, commonly used for producing the mid- and low-frequency portions of the music signal.