The language routing feature limits search queries to documents in a specified language.

Language routing makes querying more precise by reducing the number of false positive matches because documents are only analyzed for one language. Because language routing optimizes indexing performance and increases query precision, it is recommended to use it when indexing documents. Language routing requires no change to search queries.

Previously, documents were analyzed for all supported languages. This practice sometimes caused _noise_ when one language's stemming rules collided with another's.

## Add language routing on any type of object

You can add language routing to any kind of object with the `LanguageRoutingAttribute` or the conventions API.

### LanguageRoutingAttribute

You can add language routing with the `LanguageRoutingAttribute` on the property. Set it to the desired language when initializing the object.

### Conventions

Another option is to use the conventions API in Search & Navigation.

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Note

After upgrading to Optimizely Search & Navigation 13, reindex the whole site as soon as possible.