Alias name
A replacement name for files and folders, used only internally inside catalogs. Each file or folder can have its own alias name, in cases where the original file name is not very informative or friendly. Description plugins can import and set alias names as well as descriptions.
A common example of using alias names is replacing the Audio Track files (Tracknn.cda) with the Title and Author data, retrieved by the CDDB plugin.
Description
A textual, possibly multi-line description of an item in catalog. Every catalog item can have its own description, which is either imported automatically during media scan by description plugins, or edited manually by the user.
Description Module
Description module is a DLL file, used to expand WhereIsIt's description importing capabilities. Each description module can contain one or more description plugin.
Plugins
Description plugins are an add-ons for WhereIsIt that allow automated description importing from different sources. Mostly plugins are used for importing textual descriptions, however some plugins types also handle formatting of imported descriptions, or they import image thumbnails.
Thumbnail
A small graphical representation of a document, most commonly used on image file. WhereIsIt can import such small versions of image files and store them inside catalogs, making them available for preview even when files themselves are not available.