Using robots meta tags Rich Snippets
Google uses content previews, including text snippets along with other media, to help people decide whether or not a result is relevant for their query. The kind of preview shown depends on many factors, including the type of material a person is looking for and the type of device they are seeing it on.
For instance, if you try to find recipe results on Google, then you may see thumbnail images and consumer ratings–things which might be more helpful than text snippets when it comes to deciding what you wish to consume. Alternately, or maybe you’re looking for a concert nearby and are able to check out the events directly in the search results.
Google automatically generates previews in a sense meant to aid a user to understand the results displayed are related to their own search and the reason why the user would want to visit the linked pages. But, we realize that the website owner might want to separately adjust the area of their preview content in search results. To make it much easier for individual websites to define how much of that text should be available for snippeting and the degree to which other websites should be included in their reviews, we’re now introducing several new settings for webmasters.
Using robots meta tags
The robots meta tag is added to an HTML page’s <head>, or specified via the x-robots-tag HTTP header. The robots meta tags addressing the preview content for a page are:
This is an existing option to specify that you don’t want any textual snippet shown for this page.
New! Specify a maximum text-length, in characters, of a snippet for your page.
New! Specify a maximum duration in seconds of an animated video preview.
New! Specify a maximum size of image preview to be shown for images on this page, using either “none”, “standard”, or “large”.
They can be combined, for example:
<meta name="robots" content="max-snippet:50, max-image-preview:large">