Google scraping is the practice of generating high volumes of automated queries on Google’s search engine or on other Google’s properties - Google keyword generator on AdWords interface for instance.
Google scraping has many possible uses:
to establish queries statistics
to identify backlinks
to locate dofollow blog comments for comment spamming
Google scraping can be performed directly by developpers or by the way of specific tools and softwares. Large scale Google scraping is made directly through Google’s APIs
Some players like some backlink checking tools or SERP positions auditing tools sell services based upon scraped Google’s data.
Google has a strict policy regarding use of scraped data and can sometimes blocked some actors.