# Localization tables
> Understand table collections, keys, entries, and metadata.
Understand table collections, keys, entries, and metadata.
Tables store translations. Each locale has its own table, and each key has its own entry. A table collection groups the tables for every locale with the shared key registry, so you author everything in one place.
## Collection anatomy
{ /* Mermaid source kept for the future doc platform; shown as the static image below until mermaid rendering is supported. */ }
```mermaid
flowchart TD
coll["ResourceTableCollection
(Editor-only asset)"]
shared["SharedTableData
keys, IDs, Smart flags, metadata"]
t1["ResourceTable (en)
entries"]
t2["ResourceTable (fr)
entries"]
t3["ResourceTable (ja)
entries"]
coll --> shared
coll --> t1
coll --> t2
coll --> t3
t1 --> shared
t2 --> shared
t3 --> shared
classDef code fill:#F5F5F5,stroke:#BDBDBD,color:#111;
class coll,shared,t1,t2,t3 code;
linkStyle default stroke:#2196F3,stroke-width:1.5px;
```
**A table collection groups shared key data with one table per locale.:**
A table collection groups three underlying types:
* [`SharedTableData`](/engine/6000.7/script-reference/unity/localization/sharedtabledata.md) is the key registry. It contains every key with its stable ID, its Smart flag, and any shared metadata. All locales share it.
* [`ResourceTable`](/engine/6000.7/script-reference/unity/localization/resourcetable.md) holds one locale's entries. The Player loads only the tables it needs.
* `ResourceTableCollection` is the Editor-only asset that ties them together and records which content source serves them.
You can create a collection from the **Assets** menu or from the [Resource Tables window](/engine/6000.7/manual/localization/resource-tables-window-reference.md). Refer to [Create and edit table collections](/engine/6000.7/manual/localization/translations/create-and-edit-table-collections.md) for more information. Unity keeps the sibling assets in sync when you move, rename, or delete the collection.
## Keys and IDs
Every key has a stable numeric ID, assigned by a [`DistributedUIDGenerator`](/engine/6000.7/script-reference/unity/localization/distributeduidgenerator.md) so IDs stay unique across machines. A rename keeps the key's ID, so references and shipped data keep working.
Scripts refer to an entry through a [`TableReference`](/engine/6000.7/script-reference/unity/localization/tablereference.md) and a [`TableEntryReference`](/engine/6000.7/script-reference/unity/localization/tableentryreference.md). A `TableReference` selects the collection by name or globally unique identifier (GUID). A `TableEntryReference` selects the entry by key name or ID. Names read better in code, but GUIDs and IDs survive renames.
## Entry types
A key holds one of the following entry types.
| **Entry type** | **Description** |
| -------------- | -------------------------------------------------------------------------------------------------------- |
| String | A text value. The most common type, and supports Smart Strings. |
| Asset | A reference to an asset, one per locale. Common examples are localized textures, audio clips, and fonts. |
Each Asset entry also has a per-locale storage mode (Direct or Resources) that decides whether the asset loads with the table or on demand. Refer to [Localize assets](/engine/6000.7/manual/localization/translations/localize-assets.md).
## Smart Strings
Each key has a **Smart string** toggle in the table editor. A smart entry's value is a [Smart String](/engine/6000.7/manual/scripting/generate-dynamic-text/smart-strings.md) format, evaluated at resolve time with the arguments and variables you pass. The flag lives on the key, so a key uses Smart Strings in every locale or in none. To enable Smart Strings on a key, refer to [Make an entry dynamic](/engine/6000.7/manual/localization/translations/create-and-edit-table-collections.md#make-an-entry-dynamic).
## Variants
You can add variant rows to a key, so one entry holds several values chosen at runtime by a **selector**. A selector inspects the runtime environment, for example the current platform or a value your code supplies, and picks one variant row. A typical use is one value per platform.
Variants are an authoring feature of the Resource Tables window; no public scripting API exposes them. To create variants, refer to [Add variants](/engine/6000.7/manual/localization/translations/create-and-edit-table-collections.md#add-variants).
## Metadata
Entries, keys, tables, and the collection's shared data can carry metadata: serializable objects implementing [`IMetadata`](/engine/6000.7/script-reference/unity/localization/imetadata.md). The built-in types are:
| **Metadata** | **Description** |
| -------------------------------- | ----------------------------------------------------------------------------------------------- |
| Comment | A note for translators or teammates. |
| Exclude entry from player export | Unity doesn't write the entry to generated data files; it ships inside the table asset instead. |
| Exclude entry from editor export | Unity leaves the entry out of files exported for translators. |
A variant key is a key with a **Variant Selector** metadata item attached, and the **Add Entry** > **Variant** menu attaches it for you. You don't normally add this metadata manually. Refer to [Variants](#variants).
To define your own, implement `IMetadata` on a serializable class and mark it with [`MetadataAttribute`](/engine/6000.7/script-reference/unity/localization/metadataattribute.md) to control where it can attach.
## Additional resources
* [Create and edit table collections](/engine/6000.7/manual/localization/translations/create-and-edit-table-collections.md)
* [Import and export table collections](/engine/6000.7/manual/localization/translations/import-export-table-collections.md)
* [Resource Tables window reference](/engine/6000.7/manual/localization/resource-tables-window-reference.md)
* [Generate dynamic text with Smart Strings](/engine/6000.7/manual/scripting/generate-dynamic-text/smart-strings.md)