My question is what is the difference between PageRank and Page Authority? Can anybody define me please.
PageRank is Google's link analysis algorithm that assigns a numerical weighting to web pages based on the links they receive from other websites.
Page Authority is a term used by different tools, companies, individuals that can mean different things - but generally is a score assigned to a web page based on a number of factors, such as number of inbound links, quality of inbound links, social media shares & mentions, onsite SEO optimization, amongst other things.
Page Rank is a rank given to each and ever webpage by Google. This Ranking is based on the Link Analysis Algorithm named after Larry Page of Google. Page Rank is based on a logarithmic scale from 0 to 10 and its depends on the number of backlinks a webpage receiving. If you get backlink from a high PR site then your webpage PR will increase. For more information about the Algorithm Formula visit http://en.wikipedia.org/wiki/PageRank
Page authority is an SEO term used to describe the probability that a specific page from your site will be found on a search engine. Page authority is based on a logarithmic scale from 0 to 100 and deals with the relevance of information and links within site pages to one another. Higher page authority means greater chances of your page showing up on search engines, and that your page will be placed closer to the top of the search results. Note that page authority is related to the pages within sites, not the site itself. - See more at: http://www.drumbeatmarketing.net/seo-blog/what-is-page-authority
See the following for their definitions:
See the following for comparing the two:
Google PageRank Vs. SEOmoz Page Authority: Which is A Better Metric?
(Most SEM would say to focus on the later versus the former)
A Page Rank is a ranking given by google search engine where they calculate the quality and quantity of links to a webpage to give related score for that page importance. It also depends upon how popular the site is and how much time does the user spending on it. Whereas Page Authority is a metric developed by SEO Moz where they will show the ability of a page in algorithmic calculations from 0 to 100 PA score.
The main difference is that these are the similar metrics from different companies. The base of both - quantity and quality of backlinks to the page. Page Authority (PA) is more reliable and adequate metric. Google says Page Rank (PR) is quite not using in their ranking algorithm, because of easy way of manipulating on it. Both metrics are based on huge number of factors and nobody knows them all (except Google and Moz), so it is quite impossible to answer your question definitely. Use these metrics combined with other.