A world of sound comes to your desktop.

As you flip through the pages of Keyboard, you’ll see full-page ads for grand pianos, symphony orchestras, horn sections, drum grooves, and ethnic instruments from around the world. But not to worry — if you place an order, the Memphis Horns are not going to be ringing your doorbell. The magic that makes it possible for you to use these sounds in your own music productions is digital recording, also known as sampling.

A producer hires, let’s say, a symphony orchestra and a hall, sets up great microphones, and captures several days of vibrant performances (either phrases or one note at a time) into a digital recorder. After careful editing, the best bits are made available on a CD-ROM or DVD, or possibly on a stack of them.

The type of disc you buy will depend on what equipment you have in your studio. Most sound library discs are available in a variety of formats. In some cases, a single disc will provide files in several formats:

• Audio: Audio CDs are becoming obsolete as a distribution medium for sound libraries, but they’re guaranteed to be compatible with anything: You pop the CD into an ordinary CD player and re-record the output into your other equipment. But as musicians join the computer revolution, other formats are easier to use.

• WAV files: Almost any computer program that has an audio output can load WAV files. The main exceptions are analog-style synths and “closed system” programs that have their own sound libraries. (Such programs also come on CD or DVD.) WAV files, like audio CD tracks, contain nothing but sound: There’s no special formatting to make them compatible with today’s sophisticated playback software.

• Loop formats: The two most common types of loop files are Apple Loops (compatible with Apple GarageBand and other programs) and Acidized WAV (compatible with Sony Acid Pro and other programs). These file formats contain extra information that lets your software change the tempo of the loop to suit your musical needs. Note, however, that some programs, such as Ableton Live, can slice up and time-stretch any WAV file.

• REX files: This file type provides a different way of time-stretching loops. In a REX file, the loop is sliced apart by the sound developer into individual hits (for instance, every sixteenth-note). The hits are then triggered separately by MIDI notes, which are also included in the REX file. REX files can be loaded by many digital audio workstations, and also by software percussion machines such as Spectrasonics’ Stylus RMX. With a REX file, you can not only change the tempo of the loop but also change the order of the drum hits to produce an entirely different groove.

• Sampler files: Some sound libraries are sampled one note at a time so that they can be played from a keyboard. Samplers that can load these files include TASCAM GigaStudio, Apple EXS-24, Steinberg HALion, Native Instruments Kontakt, and the NN-XT module in Propellerhead Reason. Sampler files typically contain “real-world” instruments such as electric piano and string orchestra. Sound libraries prepared for a sampler will include specialized data to control the key zones, filters, and other parameters of the sampler. You don’t need specialized files to use these samplers, though: All of them will load WAV files.

• Transposing riffs: A few plug-in synths, such as Steinberg Virtual Guitarist and Virtual Bassist, ship with large sound libraries of riffs that can not only change tempo but follow chord changes in real time as you play the keyboard.

• Construction kits: Construction kits aren’t a file type — most are made up of ordinary WAV files — but they deserve special mention. A construction kit contains a number of files (both loops and individual sounds such as percussion hits) that work well together musically. A kit might include a complete mix of an eight-bar riff, the individual tracks in the mix (drums, bass, keys, guitar, etc.) by themselves, and further breakdowns such as the drums with no kick, so you can substitute your own kick sound.

As you get deeper into using sound libraries, you’ll discover issues we haven’t had room to talk about here, such as the various sampling rates and the ability of some samplers to load (imperfectly) files created for other samplers. But no matter how you slice it — or even if you don’t — sound library CDs are a great way to give your music a professional-sounding sparkle.