These are the two terms upon which the entire web world depends and all the site search and ranking depend on these two.
Now let us define, and understand, and get some depth information about crawling and indexing.
When Google visits your website for tracking purposes. This process is done by Google’s Spider crawler and its call crawling it happened automatically on server and google will update your new data in search engine to make that easily searchable which is indexing in other word.
In the Site SEO world, crawling means following your links and “crawling” around your website. When bots come to your website (any page), they follow other linked pages also on your website.
This is one reason why we create site maps, as they contain all of the links in our blog and Google’s bots can use them to look deeply into a website.
After crawling has been done all the data tracked and monitored , the results get put onto Google’s index mean all the resulted data will be added to search so visitor on google search who are searching data can see results in search with other results.
In layman’s terms, indexing is the process of adding webpages into Google search.
Its on Meta tag you used (index or NO-index), Google will crawl and index your pages. A no-index tag means that that page will not be added into the web search’s index.
By default, every WordPress post and page is indexed because its best cms for bloging .
A good idea for ranking higher in search engines is to let only vital parts of your blog/website be indexed.