Instant Previews are page snapshots that allow users to get a glimpse of the layout of the web pages behind each search result, in order to help them decide whether or not to click a link.
To see an Instant Preview, hover your cursor over a result. Then hover over the arrows that appear next to the result to see a visual preview of that result. For some previews, highly relevant parts of the page will appear in text call-out boxes over the preview image to help you see where your query appears on the page. Some results may not have previews available.
Instant Preview are extremely useful to users and can help them decide whether or not to click on your site in the search results. You can, however, specify that Google should not display Instant Preview for your page, in which case neither the text snippet nor the preview will appear.
Instant Preview is available for most types of pages in Web search results. If Instant Preview isn't available for your site, it's probably for one of the following reasons:
- The page contains a meta nosnippet tag that prevents Google from displaying snippets and previews in search results.
- Your page is blocked by robots.txt.
In general, Google updates the Instant Preview snapshot as part of our web crawling process. When we don’t have a cached preview image (which primarily happens when we can’t fetch the contents of important resources), we may choose to create a preview image on-the-fly based on a user’s request. To generate previews on the fly, Google uses the user-agent "Google Web Preview" (the fully-qualified user-agent you see in your server logs may change from time to time) to render images on demand, so you may see this in your referrer logs. If you've recently updated your page and the changes aren't reflected in Instant Preview, wait a day or so and then check again.