What is an MP3 player? In short, all MP3 players are portable devices that play digital music files--although many MP3 players can do much more than that. They evolved from the portable cassette and CD players that we carried around in the 1980s and '90s. Instead of bulky cassettes or scratch-prone compact discs, most MP3 players play files stored directly on the device. Aside from a pair of headphones, there is nothing extra you need to carry to enjoy your music collection.

What is an MP3, and how does it work with MP3 players?

MP3 stands for Moving Pictures Experts Group, Standard One, Audio Layer 3; it was developed to compress audio for storage and playback on digital devices. It essentially works by stripping out or hiding recorded sounds that are near, or beyond, the threshold of human hearing. A compact disc usually loses about 90% of its file size when it's converted to standard MP3 format. This radical reduction in file size revolutionized digital multimedia by allowing users to easily store their entire music collection on their computers.

MP3 players work by decoding the MP3 file's information, converting its binary 1s and 0s back into an analog signal that can be sent to speakers or an amplifier. Overall sound quality depends on several factors, however, the most important of which is the bit-rate of the MP3 file. This can range from 32,000 bits-per-second (or 32kbit/s) all the way up to 320,000 bits-per-second (320kbit/s). The standard MP3 is encoded at 128kbit/s, and it offers a good trade-off of sound quality to file size. Higher bit-rates offer greater sound fidelity; however, these files take more room to store. Bit-rates below 128kbit/s start to introduce noticeable sound artifacts, with 32kbit/s having comparable fidelity to AM radio broadcasts.

What is the difference between a portable media player and an MP3 player?

A portable media player (PMP) distinguishes itself from an MP3 player by having the additional ability to play digital video and display images. Because of this, they are also called portable video players. They have color screens ranging from 1.5 inches--on the ultra-portable Creative Zen V Plus, for example--all the way up to 7 inches on the robust Archos 705. Except for the iPod Shuffle, the entire current iPod line can play both video and audio files.

Can I watch videos on an MP3 player?

"MP3 player" is generally used as a catch-all term that also includes portable media player devices. While all portable media players have the ability to play MP3 files, not all MP3 players can play video. Strictly speaking, dedicated MP3 players do not play video files. They typically have smaller form factors because they lack the larger screen that portable media players have. The iPod shuffle, SanDisk Sansa Clip, and Creative Zen Stone are good examples of dedicated MP3 players, and, as such, they do not play video.

What types of players are there?

MP3 and portable media players are generally categorized by how they store data. Manufacturers use one of three mediums to store data; each impacts the size, capacity, and cost of the device, as well as its overall durability.

Hard-Drive Based Players

These media players store information on small hard-drives, much like the ones used in laptops or home computers. Inside the hard-drive, a set of magnetic discs spin very quickly while a magnetic "head" whips back and forth to read and write data. Hard-drive-based MP3 players continue to have the highest capacity of all storage types; however, they tend to be larger and heavier because of the hard drive and battery size. Due to tiny, high-speed moving parts, these players can malfunction if they are dropped or exposed to very hot temperatures. If you are looking for a high-capacity MP3 player and don't plan on subjecting it to regular abuse, a hard-drive based player is right for you.

Flash Memory-Based Players

Unlike hard-drive based players, flash memory players have no internal moving parts that can malfunction. Data is stored on a solid-state chip covered in transistors. This results in players that are smaller and much more durable than those that incorporate other technologies. These advantages do come at a very tangible price, though. Flash memory is still the most expensive way to store data on MP3 players. A 16 GB iPod Touch, which uses flash memory, retails for almost $50 more than a 160 GB hard-drive based iPod Classic that holds 10 times as much data. These players are well worth the price for active, on-the-go users, or for those who want a tiny MP3 player that can unobtrusively fit in any pocket.

CD MP3 Players

Most people don't think of CDs when they think of MP3 players, but many car audio receivers and portable compact disc players manufactured today can read discs that have been written in MP3 format. CD MP3 players look and operate just like their older counterparts (portable CD players), and are generally the least expensive of the three types. They are fundamentally different from other kinds of MP3 players, since you must purchase blank CDs and record your own MP3-encoded music onto them. A typical compact disc holds 700 MB of information, which is equivalent to about 15 albums. If you're looking for an inexpensive MP3 player and aren't bothered by buying, burning, and carrying additional CDs, a CD-based player would be perfect for you.