3. Page Rank (PR):

Page rank is the ranking system of google.com and values from 0-10. The more the page rank, the better the earnings from the ads and better the trust of users. 

Page rank of a website depends upon the number of good quality backlinks (that already have some PR), pointing toward your domain.

eg: twitter.com PR 10, Google.com PR 9

You could check your domain PR from PageRankChecker.com
4. Sitemap XML/HTML: 

As the name suggests, it is the map of a website. It is used to define the website addressing of each web page and how is it linked. It is mainly used for webpage updations like adding pages to a website or deleting them. Accordingly, the sitemap is updated to search engines every time.

It compels the search engine crawler to Crawl, Cache & Index the website. Also, the total number of pages in a website could be found using its sitemaps.

There are many types of sitemaps, but the .xml and .html is widely used. 

eg: sitemap.xml          for Search Engine Crawlers
      sitemap.html        for Human understanding

The sitemap for a particular website could be generated using
xml-sitemaps.com and could then be downloaded and uploaded in to your website. 

For a good SEO, the sitemap path in a particular website should be like: domain/sitemap.xml