Listening to music on computers took off when the MP3 file format was developed in the early 1990s. This format enabled computer users to compress music into digital audio files with little loss of quality. These days, you can create MP3 files quickly from a CD, store them and play them back on a personal computer, transfer them to a portable MP3 player, and/or burn them back onto a blank CD. To get started downloading music, you need a software application that can manage and play your MP3 files. Many computers arrive with such programs installed. Some of the most popular MP3 software is available for free, including:

Winamp
the RealOne Free Player
Microsoft's Windows Media Player
iTunes for Macintosh
X MultiMedia System for Linux systems

Many of these outfits will try to get you to trade up to their more advanced players for a modest price. Plenty of music itself is available throughout the Internet. Some musicians make their songs available for free in an effort to gain more exposure and court fans. Some music is available for a fee from subscription services and may be protected by digital rights management (DRM). This encryption is designed to prevent illegal use and may compromise listening flexibility. (If you stumble upon a network of music lovers who freely share the music files on their computers, be forewarned: The recording industry has targeted many such sites and individual users for copyright infringement.) Keeping It Legal The safest places to download music are subscription-based sites affiliated with the record companies. Here are a few options:

eMusic.com. eMusic claims to be the biggest of the music sharing services, with more than 200,000 songs, 17,000 albums, and 10,000 artists. Conveniently, you can download as many complete albums or individual songs as you want. Through licensing agreements, eMusic offers selections from more than 900 music labels, including many obscure independents. The Vivendi Universal affiliate also has access to Universal Music Group's huge back catalogue. But not everything from UMG's Decca, MCA, Mercury, and Motown library is available. A recent search for Motown, Beatles, and Rolling Stones cuts found nothing. eMusic's MP3 files carry no DRM restrictions, so they can be burned to a CD, transferred to a portable MP3 player, or copied multiple times.

Read the simple tutorial about downloading files. Search the listings by artist, album, track, or label. When you've found a title you want, you can listen to a 30-second preview before you decide if you want to download the entire cut. Genres include alternative/punk, rock/pop, jazz, electronic, urban/hip hop, world/reggae, country/folk, blues, classical, new age, inspirational, and soundtracks/other. Sign up for a free two-week trial to get 50 MP3s free. A year's subscription costs $9.99 a month; three months costs $14.99 a month.

MP3.com. MP3.com, another Vivendi affiliate, started in 1997 as a way for emerging artists to get exposure. It features streaming and downloadable music from more than 200,000 artists—in all, more than 1.2 million audio files. Fans can find top 40 charts for a variety of genres, including comedy, Latin, and metal.

The site's software guide offers handy directions for listening to MP3s, converting CDs to MP3s, and managing your MP3 collection. You also can get customized song recommendations by e-mail. If you sign up, the site bumps you over to eMusic.com and offers the same free two-week trial, three-month ($14.99/month), and one-year ($9.99/month) subscriptions.

PressPlay. PressPlay features tracks from Sony, EMI, and Universal Music Group (Vivendi). Its 100,000+ songs are Windows Media DRM protected and expire after a subscriber's membership ends. Only portable downloads, which can be burned to a CD or transferred to a compatible portable player, are permanently installed in members' computers. Search results include a column of options on the right. Icons indicate if the track can be streamed, downloaded, or burned or transferred in a portable download. And portable downloads can be burned or copied only once. Like many other services, PressPlay recommends similar artists that reflect your search choices when looking for music. PressPlay offers a free three-day trial and three tiers of membership: $9.95 a month gets you unlimited streams and downloads; $17.95 a month allows you to add 10 portable downloads per month; and the $179.40 annual plan gives you 120 portable downloads on the first day of membership, in addition to unlimited streams and downloads. You can buy additional portable downloads for about $1 a cut. PressPlay won't work on Macs, Windows 95, or Windows NT. And you won't find the Beatles or Beach Boys on PressPlay. Sign up for PressPlay through one of five affiliates—MP3.com, Yahoo, Roxio, MSN Music, or Sony's Musiclub.

RealOne Music. The Real Network, which supplies the popular RealOne Player, also offers 75,000 song files as part of its RealOne Music download service. Content is provided by MusicNet, which has agreements with BMG, EMI, Warner, and Zamba. Artists in the catalogue include Neil Young, Miles Davis, and the Red Hot Chili Peppers. RealAudio tracks expire when membership lapses. Members are allowed 100 downloads and 100 streams a month for $4.95 in the basic Music Intro package. The $9.95/month RealOne Music Pass adds access to ad-free radio, more player features, and telephone support. The RealOne SuperPass Gold, $19.95 a month, adds audio and video programming in news, sports, and entertainment.

Listen.com. Listen.com offers what it calls a "celestial jukebox" in the form of its Rhapsody player and music service. It promises access to 15,000 albums from 6,000 artists in every imaginable music genre through agreements with the five biggest music companies—BMG, EMI, Sony, Universal, and Warner. You'll find Jeff Beck and the Bee Gees, but no Beatles or Beach Boys. Members have unlimited access to streams from this huge catalogue, but can't store the music on their computers. Seven-day free trials are available. If you withhold your credit card, you only get to listen to 30-second clips from the catalogue. Provide your credit card info, and you get a free trial of the full All Access service, which costs $9.95 a month. Also for $9.95 a month, you can sign up for the Naxos Classical With Burning service that allows unlimited listening to the classical catalogue and CD burning of 10 tracks a month.

Also, check out the Recording Industry Association of America's website for more legal music-download sites.