Glossary

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AAX: Avid Audio eXtension — the plugin format of Pro Tools. No other host loads it, and anyone working in Pro Tools needs it: a VST3 cannot be used there.
ARA: Audio Random Access — not a plugin format of its own but an extension. It gives a plugin access to the whole audio file instead of only the block currently playing; Melodyne and RipX work this way.
Audio to MIDI: Turning a recording into notes. A hummed melody or a guitar line becomes MIDI that can be edited freely — reliable with monophonic material, less so with chords.
Audio Unit (AU): Apple's plugin format, built into macOS. Logic Pro and GarageBand load Audio Units only; other macOS hosts load them alongside VST3.
AUv3: The third generation of Audio Unit and the only plugin format that also runs on iOS and iPadOS. Each plugin runs in its own process, so a crash does not take the host down with it.

Bit depth: How finely a single sample is resolved. 24-bit is usual when recording and leaves headroom; 16-bit is the CD's delivery format.
Buyout: In commissioned music or session work: the client acquires full usage rights for a single sum, with no later royalties.

CLAP: CLever Audio Plugin — an open, licence-free format presented in 2022 by u-he and Bitwig. It supports per-note parameter modulation and uses multiple CPU cores better; host support is growing but smaller than VST3's.
Collection page: A page that is not a tool itself but lists many — a maker's overview, a shop, a directory. It appears in the catalogue as an entry only when expressly approved as one.
Command line: A tool without a window, driven by commands. Unbeatable for batch processing and automation, awkward for everything else.

DAW: Digital Audio Workstation — the program in which recording, arranging, mixing and mastering happen. It is also the host for plugins, and thus the centre of nearly every production.
Decent Sampler: A free sampler with an open library format. It has become the usual home of independent and free sample libraries, because nobody needs a licence there.
Desktop app: A program for Windows, macOS or Linux that stands on its own — as opposed to a plugin or a web interface.

EXS24 / Sampler: The sampler built into Logic Pro. Libraries in EXS format run without an extra purchase, but only inside Logic.

Free: Usable without paying. That says nothing about the source code: a free plugin can be closed, can require an account, or can cost money in a later version.

Headroom: The distance between the loudest point of a signal and the level at which it clips. Leaving it while recording and mixing is what gives mastering something to work with.

Kontakt: Native Instruments' sampler and the de facto standard for commercial sample libraries. Many libraries are NOT standalone instruments but require Kontakt — sometimes the full version, not the free player.

Latency: The delay between playing and hearing. It comes from buffers and processing; while recording it becomes distracting from about ten milliseconds, while mixing it does not matter.
Library / API: Not a program with an interface but code or a service to build in — for developers pulling audio or MIDI features into their own software.
LV2: A free plugin format, at home above all in the Linux audio world. It succeeds LADSPA and is found in hosts such as Ardour and Qtractor.

Mastering: The final step: the finished mix is prepared for release — level, tonal balance, format. It does not replace a good mix, and it will not turn a bad one into a good one.
MIDI: Not sound but control data: which note, how hard, how long. That is why a MIDI recording can be changed freely afterwards — and why it only sounds as good as the instrument playing it.
Mixing: Bringing the individual tracks together into a whole: levels, panning, tonal shaping, space. The aim is that every element stays audible without the mix getting crowded.
Mobile app: An application for iOS, iPadOS or Android. On iOS it can additionally run as an AUv3 inside a mobile DAW.

Open source: The source code is public and may be reused under a licence. Almost always free of charge as well, though one does not follow from the other.
Oversampling: Processing at a raised sample rate inside an effect. It avoids aliasing in non-linear processing — distortion, saturation, compression — at the price of CPU load.

Plugin: A program that does not run on its own but inside a host — usually a DAW. It receives audio or MIDI from the host, processes it and hands it back.
Preset: A stored setting for an instrument or effect. Presets are the fastest way to a sound and the slowest way to one of your own.
Purchase: Pay once, use indefinitely. Upgrades to a new major version often cost again — what a purchase includes is up to the maker.

Rent-to-own: Instalments leading to ownership: you pay monthly and own the licence once the full price is reached. Stop early and the money is gone — but unlike a subscription, finishing leaves you something.

Sample rate: How often per second the signal is measured, given in kHz. 44.1 kHz is the CD standard, 48 kHz the video world's; higher rates help during processing and cost CPU time.
SFZ: An open sampler format described in plain text. It is tied to no single program and is read by several free samplers.
Side-chain: A second signal controls an effect without being heard itself. The best-known case: the kick drum briefly ducks the bass so both have room.
Sponsored: An entry whose placement was paid for. It is marked as such and stands first in lists — the marking is not a courtesy but a legal requirement.
Standalone: The same tool as a program of its own, without a host. Handy for practice and for the stage; getting a recording into a project then takes a detour.
Stem: Several tracks summed into one file — all drum tracks as one stem, all vocal tracks as another. They are handed on so somebody else can mix without needing the whole project.
Stem separation: Splitting a finished mix back into its parts — vocals, drums, bass, the rest. What used to be impossible is now done in seconds by trained models, with audible limits.
Subscription: A running payment for use. When the payment stops, access usually stops too — the decisive difference from a purchase, and one that only shows up later.

Topline writing: Writing melody and lyrics over an instrumental that already exists. A role of its own in production, often commissioned separately from the beat.

VST: Virtual Studio Technology — the plugin format Steinberg introduced in 1996, still the most widespread. "VST" without a number usually means the older VST2; new instruments and effects ship as VST3.
VST2: The second generation of the VST format and the standard for two decades. Steinberg has issued no new licences since 2018, though many hosts still load existing VST2 plugins.
VST3: The third generation of the VST format. It adds side-chain inputs, processing that switches off during silence, and orderly parameter handling. Since Steinberg stopped licensing VST2, VST3 is the format new plugins ship in.