: Often written as q=0.9 , this is a Relative Quality Factor . It ranks user preferences on a scale from 0.0 to 1.0. A value of 0.9 indicates it is a secondary preference if a primary language (defaulting to q=1.0 ) is unavailable. 2. Practical Application: How Servers Use It
When a web browser sends a request, it might include a header like: Accept-Language: en-US, th-TH;q=0.9 0.9,th-TH
: Used by clients to request specific data formats or localized error messages from RESTful APIs. Summary Table: Component Meanings th Language Code ISO 639-1 code for Thai TH Region Code ISO 3166-1 alpha-2 code for Thailand 0.9 90% weight ; high priority but not the absolute first choice : Often written as q=0
The string breaks down into two distinct parts defined by the HTTP/1.1 specification : It communicates a user's preference for Thai (Thailand)
This string is a specific component used in , specifically within the Accept-Language header. It communicates a user's preference for Thai (Thailand) with a weighted "quality" (q-factor) of 0.9 . 1. Technical Decomposition
: Developers use these strings to match user OS settings with available translation files.