In Trilium, attributes are key-value pairs assigned to notes, providing additional metadata or functionality. There are two primary types of attributes:

1. Labels can be used for a variety of purposes, such as storing metadata or configuring the behavior of notes. Labels are also searchable, enhancing note retrieval.

   For more information, including predefined labels, see Labels.

2. Relations define connections between notes, similar to links. These can be used for metadata and scripting purposes.

   For more information, including a list of predefined relations, see  Relations.

These attributes play a crucial role in organizing, categorizing, and enhancing the functionality of notes.

Types of attributes

Conceptually there are two types of attributes (applying to both labels and relations):

1. System attributes
   As the name suggest, these attributes have a special meaning since they are interpreted by Trilium. For example the color attribute will change the color of the note as displayed in the Note Tree and links, and iconClass will change the icon of a note.
2. User-defined attributes
   These are free-form labels or relations that can be used by the user. They can be used purely for categorization purposes (especially if combined with Search), or they can be given meaning through the use of Scripting.

In practice, Trilium makes no direct distinction of whether an attribute is a system one or a user-defined one. A label or relation is considered a system attribute if it matches one of the built-in names (e.g. like the aforementioned iconClass). Keep this in mind when creating  Promoted Attributes in order not to accidentally alter a system attribute (unless intended).

Viewing the list of attributes

Both the labels and relations for the current note are displayed in the Owned Attributes section of the Ribbon, where they can be viewed and edited. Inherited attributes are displayed in the Inherited Attributes section of the ribbon, where they can only be viewed.

In the list of attributes, labels are prefixed with the # character whereas relations are prefixed with the ~ character.

Attribute Definitions and Promoted Attributes

Promoted Attributes create a form-like editing experience for attributes, which makes it easy to enhancing the organization and management of attributes

Multiplicity

Attributes in Trilium can be "multi-valued", meaning multiple attributes with the same name can co-exist. This can be combined with Promoted Attributes to easily add them.

Attribute Inheritance

Trilium supports attribute inheritance, allowing child notes to inherit attributes from their parents. For more information, see Attribute Inheritance.