This takes them out of the equation and clearly signals to Google which pages they should crawl.
There are a number of ways to do this. For Crystal Carter, Head of SEO Communications at Wix, this means first of all excluding pages in robots.txt that you don't need Google to crawl because you don't want them to rank. This can be low value pages, landing and campaign pages, duplicate tag and category pages, or customer order pages. This takes them out of the equation and clearly signals to Google which pages they should crawl.