The browser will subsequently use those topics to calculate top topics for the
current user for future epochs.

See [ Using the Topics API ](/en-US/docs/Web/API/Topics_API/Using) for more
details.

Header type  |  [ Response header ](/en-US/docs/Glossary/Response_header)  
---|---  
[ Forbidden header name ](/en-US/docs/Glossary/Forbidden_header_name) |  no   
  
##  Syntax

http

    
    
    Observe-Browsing-Topics: ?1
    

###  Directives

` ?1 `

    

A character sequence declaring that topics of interest inferred from a calling
site's URL (i.e. the site where the ad tech ` <iframe> ` is embedded) are
marked as observed. The browser will subsequently use those topics to
calculate topics of interest for a user for future epochs.

##  Specifications

This feature is not part of an official standard, although it is specified in
the [ Topics API Unofficial Proposal Draft ](https://patcg-individual-
drafts.github.io/topics/) .

##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ Topics API ](/en-US/docs/Web/API/Topics_API)

##  Help improve MDN

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