Each link to the page you are considered as a vote. Links from pages that have a higher PageRank is deemed to have excellent vote values. Google gives more attention to the link and take it as an important vote. In addition, more and more links will strengthen the value of PageRank. But the links from sites that are banned will not be counted. It was like, a site that is banned as people who lost their political rights.
The addition of a the page can decrease PageRank the page. May effects the total PageRank of all the page increases. But there may be pages that will decrease the PageRank. It is uncertain how much of the decline, it may be small. Because if seen on the news websites, their pages being added every day maybe even every hour. Front page of their site PR value may remain, but in the pages of 'inside' that there may be decline. Because it may reduction in the pages inside so the decline is not felt. Our attention may only exist on certain pages.
Do not think if you've already got PR4 then it is value for you forever. There are increase and decrease. There is always a possible reduction. Can also occur because the sites that give links to you are declining its PageRank and you site will also drop.
The linkage of link is very important. The quality of the site from link that you get or links that you provide to them. The more closely related and the relevance of the theme sites that provide links will add meaning. Logically, if a visitor visiting your site because a theme and then they get a link on the page your and go to another page which gives a deeper knowledge about the theme, the visitors will give an appreciation of your site. Your site is considered to provide guidance to their problems. The visitors will consider your site meaningful. So it is with Google.
If your site is reviewed by famous sites and have good PR, be thankful. This can bring visitors to your site. Especially if they write down the link to your page. Google will really count on it. Increasingly have a good reputation, incoming links will more valuable.
But be careful of sites that are banned. If you provide a link (to write the link to their page) to a site that is banned, most likely your site is affected. The sites are banned as carry the virus. If connected with them, you could have contracted the virus.
If you carefully read the paragraph above. Each the paragraphs above explain a point that affects the PageRank of a site.
