# Glossary¶

This document is currently a work-in-progress QIIME 2 terminology glossary.

Action
A general term for a method or visualizer.
Artifact
Data that can be used as input to a QIIME method or visualizer, or that can be generated as output from a QIIME method. Artifacts typically have the extension .qza when written to file.
Method
An action that takes some combination of artifacts and parameters as input, and produces one or more artifacts as output. These output artifacts could subsequently be used as input to other QIIME 2 methods or visualizers. Methods can produce intermediate or terminal outputs in a QIIME analysis.
Parameter
A primitive (i.e., non-artifact) input to an action. For example, strings, integers, and booleans are primitives. Primitives are never output from an action.
Pipeline
A combination of actions. This is not yet implemented.
Plugin
A plugin provides microbiome (i.e. domain-specific) analysis functionality that is accessible to users through a variety of interfaces built around the QIIME 2 framework. Plugins can be developed and distributed by anyone. In more technical terms, a plugin is a Python 3 package that instantiates a qiime2.plugin.Plugin object, and registers actions, data formats, and/or semantic types that become discoverable in the QIIME 2 framework.
Result
A general term for an artifact or visualization. A result is produced by a method, visualizer, or pipeline.
Visualization
Data that can be generated as output from a QIIME visualizer. Visualizations typically have the extension .qzv when written to file.
Visualizer
An action that takes some combination of artifacts and parameters as input, and produces exactly one visualization as output. Output visualizations, by definition, cannot be used as input to other QIIME 2 methods or visualizers. Visualizers can only produce terminal output in a QIIME analysis.