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Understand the data
Entries, kinds, concepts, connections, and citations explained.
Five terms explain most of the catalog: entry, kind, concept, connection, and citation.
An entry is one record with its own page. A person, a building, a film, and an equation can all be entries. They share a basic record structure, which lets the same views explore them together.
Entries hold useful summary information. Longer explanations remain in linked articles, books, papers, and other sources.
A kind determines which facts an entry can hold. Buildings have fields such as height and floors; people have birth and death years. Technical documentation calls a kind a type.
An entry can have more than one kind when each applies. A restaurant, for example, may be both an organization and a place.
A concept classifies an entry by a style, movement, subject, period, material, or similar characteristic. Building is a kind; Art Deco is a concept that can classify a building.
Concepts can have broader and narrower terms, making it possible to browse from a broad category into a more specific one.
Some concepts also have their own entries. This allows a connection to point to the idea itself, such as a movement influenced by a person. The classification term and its linked entry serve different purposes.
A connection links two entries and describes their relationship. It can include an explanation, dates, and citations.
Specific labels belong to six broad families, the connection kinds:
| Family | Meaning |
|---|---|
| Influence or lineage | One thing influenced, developed from, or followed another. |
| Similarity | Two things are alike in a recorded way. |
| Co-occurrence | Two things occur, appear, or are used together. |
| Part-of | One thing belongs to a larger whole. |
| Contrast or opposition | Two things are opposed or contrasted. |
| Cause | One thing is recorded as increasing or reducing another effect. |
Similarity, co-occurrence, and opposition are symmetric: the relationship reads in both directions. Influence, part-of, and cause are directional. The interface uses the appropriate label for the end you are viewing.
A causal connection also records a positive or negative effect. That sign describes the claim; it does not prove causation or measure its strength.
A source is a reference, such as a book, article, dataset, or webpage. A citation connects that source to an entry, one of its facts, or a connection.
Some citations support a claim; others record a disagreement or identify the dataset a value came from. Read the source to understand the context. Unsourced means no citation is attached to the displayed fact.
Entries can record a start year, end year, display text, and date precision. BCE years are supported. The meaning of a date depends on the entry: a person's lifespan, for example, differs from a building's construction period.
Approximate dates are labeled in the record, but charts still place them at a numerical position. Use the entry's details when precision matters.
The commons is the shared catalog: entries, classifications, connections, and sources. The overlay is the project's separate model for personal notes, tags, favorites, and collections. Personal features are not available on the public site.
Editorial Stories are guided narratives built from catalog records. They are distinct from the catalog's Fictional Story and Nonfictional Story entry kinds (see story).
For classification examples, read Classification. For implementation details, read Architecture.