Google Crawling: Whenever Google Spider comes on your web page, it leaves a thread in each link and searches for the required information. The process of searching information on your webpage and going deep in the links is called Crawling.

Google Cache: Once the Spider has come and after crawling the page, it take a copy of that page (if required) and leaves a date and time when it crawled your page, that date and time is called as Google Cache also Caching is where copies of web pages stored locally on an Internet user’s hard drive or within a search engine’s database.

Google Indexing: After crawling, caching the page, the spider takes the copy of that web page with it and saves it on the Google Server, this process of saving the web page on its server is called Google Indexing. So whenever you see For ex: that you 20 or 30 pages are indexed, this means Google has taken a copy of those 20-30 pages and those are saved on its server.