In the World of Smartphones, Google wants to make happy users on all devices like desktop, mobile, tablet etc. so that for users it will be easier for them to read or navigate to the site easily.
On the basis of this, Google has come up with a new term named “Dynamic Serving”.
Now, the first question arises in your mind is “what is that, Dynamic serving now ??”
So, the answer for your question is here :
Dynamic serving is a setup where the server responds with different HTML (and CSS) on the same URL depending on the user agent requesting the page.
As it is not immediately apparent in this setup that the site alters the HTML for mobile user agents (the mobile content is “hidden” when crawled with a desktop user agent), we recommend that the server send a hint to request that Googlebot for smartphones also crawl the page, and thus discover the mobile content. This hint is implemented using the Vary HTTP header.
- Use the Vary HTTP header to signal your changes depending on the user-agent.
- Detect user-agent strings correctly.
Find more details on our developers site: http://goo.gl/TAeDqS.