Crawl simply means discovery of new content by search engine and analyze it. Content may be web page, video, pdf, image. Googlebot uses an algorithmic process to crawl web pages. Googlebot visits web pages and adds them to its list of pages to get crawl.
Indexing means the web page is eligible to show up in Google’s search engine results. The web page being crawled does not necessarily mean it have been indexed. To know if your web page is indexed or not, go to google and visit site:yourdomain , e.g site:himalweb.com
If you found that some of the web pages are missing, you can index it by submitting sitemap in google search console. Follow this link for tutorial. https://www.youtube.com/watch?v=ExKynNMzxJY
Also for better search result fill meta tag description
So, do you want to get on top in search result. Google always focus on providing useful answer to searcher question in good format. Backlink is the link of your website(site A) that have been put in other website(site B). Backlink is done for referral, sharing blog, testimony, etc. More genuine backlink is factor for increasing your website ranking. There are also other factor like website speed, internal link, etc for good ranking in google search result.
This link (https://moz.com/beginners-guide-to-seo)
explain the best about seo
The technique and strategies followed by search engine rules and regulation is White hat seo.
The technique and strategies which spam and fool search engine is Black hat seo.
Once search engine have identified you have been spamming and fooling them, you will be punished by them. This is why you should be very careful choosing seo expert or agency.\