Why my page rank gradually decreasing?

Generally Blogger have this question.

Q: I have many download links in my blog to xyz.com, i have seen my page rank gradually decreases, while adding more links??Why and what is the soluation?

Ans: Yes… Because you are linking to external website so some of your blog’s link juice will link to other sites resulting in decrease page rank… To avoid link juice linking you can add rel=”nofollow” tag to download link.

What is rel=nofollow?

Ans:   nofollow is an HTML attribute value used to instruct some search engines that a hyperlink should not influence the link target's ranking in the search engine's index. It is intended to reduce the effectiveness of certain types of search engine spam, thereby improving the quality of search engine results.

The concept for the specification of the attribute value nofollow was designed by Google’s head of webspam team Matt cutts and Jason Shellen from Blogger.com in 2005.

The nofollow HTML attribute was originally designed to stop comment spam on blogs. Believing that comment spam affected the entire blogging community, in early 2005 Google’s Matt Cutts and Blogger’s Jason Shellen designed the attribute to address the problem.

 

Example:

<a href="http://en.wikipedia.org/wiki/Nofollow" rel="nofollow"></a>

This is and example as well as if you want to read more about rel=nofollow

you can click on above link.

Example, assume that Google has assigned a web page some

100 points and there are 5 hyperlinks on that page. Each

of these pages will therefore get 20 points from Google. 

If two of these hyperlinks are written using the  

rel=nofollow attribute, Google won’t give them any 
points but the remaining three pages will still get 20 

points each as before. The balance 40 points (100 – 20*3) 

are lost. 

Note: you should not use nofollow for internal link.