An object can be classified by what it is, what it is made of, what it does, where it came from, what state it is in and how it relates to other objects.
A hammer is a tool, a metal-and-wood object, a manufactured product, a hand-held device and perhaps an archaeological artefact. A smartphone is a communication device, computing device, consumer product, network node and personal possession. One label rarely captures all useful meaning.
Quick answer: how should objects be categorised?
- Type: what kind of object is it?
- Material: what is it made from?
- Structure: what parts compose it?
- Function: what is it designed or used to do?
- State: active, damaged, empty, charged, broken, assembled?
- Origin: natural, manufactured, modified, derived?
- Ownership: who owns or controls it?
- Location: where is it now?
- Lifecycle: new, in use, repaired, retired, recycled?
- Relationships: part-of, contains, attached-to, derived-from, used-with?
This article applies How to Categorise Anything to physical and digital objects.
1. Define the object boundary
Decide whether you are classifying one component, one assembled item, one set or one system. A wheel, bicycle and bicycle fleet are different units.
2. Type asks what kind of thing it is
Chair, camera, molecule, vehicle, document and software package are type classifications.
3. Type should not absorb every property
Red, heavy, broken and Singapore-made are properties or contextual attributes, not necessarily object types.
4. Material is an independent dimension
Wood, steel, glass, ceramic, polymer and composite describe composition.
5. One object can contain several materials
Material classification is often multi-valued and may include proportions or layered structure.
6. Structure describes organisation of parts
An object can be solid, hollow, modular, layered, articulated or networked.
7. Parts need typed relationships
A battery is part of a phone, not a kind of phone. Preserve part-of separately from is-a.
8. Function describes intended job
Cutting, measuring, communicating, containing and supporting are functions.
9. Intended function and actual use can differ
A cup may be used as a pencil holder. Record designed-for and used-as separately when useful.
10. Multi-function objects need multiple labels
A smartphone functions as camera, communicator, computer, payment device and sensor platform.
11. Natural and manufactured origin differ
A stone, shell and leaf may be natural objects; a bottle and circuit board are manufactured.
12. Modified natural objects form another class
Cut timber, polished stone and preserved specimens combine natural origin with human transformation.
13. Digital objects complicate materiality
A file has no simple physical material identity, yet it has format, size, encoding, version and storage location.
14. Digital object and physical carrier should be separated
The same file can exist on several drives while remaining one logical content object.
15. State is temporary
Open, closed, charged, empty, damaged and calibrated are states that can change without changing object identity.
16. Condition is not type
A broken chair remains a chair while its condition changes.
17. Lifecycle classification tracks change
Prototype, new, active, maintained, repaired, refurbished, retired and recycled describe different lifecycle stages.
18. Repair does not necessarily create new identity
Identity rules should state when component replacement produces the same object versus a new object.
19. Version matters for manufactured and digital objects
Model, revision, firmware and edition can alter function while preserving product-family identity.
20. Ownership is contextual
Owned-by, leased-to, controlled-by and held-in-custody are distinct relationships.
21. Possession is not ownership
An archive, warehouse or borrower can possess an object without owning it.
22. Location changes independently
Store current location separately from origin, manufacturer and owner.
23. Objects can be mobile or fixed
A building, machine tool and vehicle differ in mobility even when all are manufactured assets.
24. Scale matters
Microscopic particles, handheld tools, buildings and spacecraft require different descriptive properties.
25. Measurement properties should remain attributes
Mass, length, volume, capacity and power are often better represented numerically than converted into many category labels.
26. Threshold categories can still be useful
Small, medium and large may support operations, but boundaries should be explicit.
27. Value is not intrinsic type
Expensive, rare, collectible and strategic are context-dependent evaluations.
28. Safety class is another facet
Hazardous, fragile, sterile or regulated handling can coexist with ordinary object type.
29. Historical significance is contextual
An ordinary object can become historically important because of provenance or association.
30. Provenance can change interpretation
Two visually identical objects may have very different evidential or cultural value because of origin and custody.
31. Similarity can assist object classification
Shape, texture, image and embedding similarity can generate candidate categories for unfamiliar objects.
32. Similar appearance can hide different function
Visual similarity should not override material, mechanism or regulatory distinctions where those matter.
33. Rule-based classification can enforce hard constraints
Material thresholds, dimensions or certification status may determine operational categories exactly.
34. Unknown objects need rejection states
Do not force an unfamiliar object into the nearest category when evidence is weak.
35. Collections create another level
A toolkit, museum collection and inventory batch group objects through ownership, purpose or provenance rather than type alone.
36. Objects can belong to systems
A sensor may be part of a building-control system, a satellite or a laboratory setup. System role should be represented relationally.
37. A practical object record
- object ID;
- type;
- materials;
- parts;
- functions;
- origin;
- manufacturer or creator;
- state;
- condition;
- version;
- owner;
- location;
- lifecycle stage;
- relationships;
- confidence;
- taxonomy version.
38. Use facets for independent properties
Material, function, condition, location and ownership should not all become branches of one type tree.
39. Use ontology for complex object systems
Typed relationships preserve assemblies, components, versions, ownership and use more faithfully than flat tags.
40. The deeper idea
An object has identity, properties, states and relationships. Good classification keeps those layers separate enough that one can change without rewriting the others.
To classify an object well is to distinguish what it is from what it is made of, what it does, where it is, who controls it and what has happened to it.
Final answer
Categorise objects by type, material, structure, function, origin, state, condition, ownership, location, lifecycle and relationships. Keep part-of separate from is-a, distinguish intended function from actual use, and use stable identifiers so state, ownership and location can change without changing object identity.