Where the Crawl is a process by which the Google Search Appliance discovers enterprise content and creates a master index. That is the resulting index consists of all of the words, phrases, and meta-data in the crawled documents.

And when users search for information, their queries are executed against the index rather than the actual documents. The Searching against content that is already indexed in the appliance is not interrupted, even as new content continues to be indexed.

Google Crawling or web crawling refers to an automated process through which search engines filtrate web pages for proper indexing.

Web crawlers go through web pages, look for relevant keywords, hyperlinks, and content, and bring information back to the web servers for indexing.

As crawlers like Google Bots also go through other linked pages on websites, companies build sitemaps for better accessibility and navigation.

Indexing 

Indexing starts when the crawling process gets over during a search. Google uses crawling to collect pages relevant to the search queries and creates an index that includes specific words or searches terms and their locations.

Search engines answer queries of the users by looking up to the index and showing the most appropriate pages.