0.9,fr-fr

Are you trying to or set up language detection for a specific web application? The role of Accept-Language header in software localization

: If fr-FR is not available, it may look for a general French version ( fr ) or the next language in the user's priority list. 0.9,fr-FR

The string "0.9,fr-FR" is typically a segment of an , which tells a web server which languages a user prefers for the content they receive. Understanding the Syntax Are you trying to or set up language

A full header might look like this: Accept-Language: en-US,en;q=0.9,fr-FR;q=0.8 This tells the server: "I prefer US English (1.0), but I'll take any English (0.9) or French from France (0.8) if that's what you have". Understanding the Syntax A full header might look

: Developers use these strings in languages like Python (Flask) or Node.js to automatically redirect users to the correct localized version of a site. Common Example

In this context, the values indicate a prioritized list of preferences: : This specifies French as spoken in France .

: The "q" (quality value) is a weight from 0.0 to 1.0. A value of 0.9 indicates a high priority, though typically slightly lower than the primary language (which defaults to 1.0 if not specified). How Servers Use It