The subject of copying ,Plagiarism and Blogposts is very complicated.

People write posts to be read widely.

One has to authenticate a Story or information in a Post.

(As when you write on Subjects, .present research papers where you need authenticity.

You then have open sources like wiki.)

If one is commenting on an issue,one has to quote the source.

While quoting ‘portions of the news,Story has to be posted in the post one is writing.

What is Plagiarism in a Blog?

In general quoting some one else’s post/information  word for word ,quotes without permission,or quoting information provided by others as one’s own with slight modifications.is generally classified as Plagiarism.

If one were to post entirely on one’s own, the post may not be interesting without references, , in the case of information, there will be lack of authenticity.

And again Link building?

Does it not amount to using others whole posts under one Link?

There is no answer to this query.

There are soft-wares to check Plagiarism.

Copyscape is one good site, where one gets to know how the material of similar nature is in the web and it calculates and lets you know what percentage of words are in common.

And there is also the point of Google penalizing your site for Plagiarism and thee are chances of Google Page ranker passing over your site.

You may find more information on Plagiarism, Penalty for Plagiarism at

http://www.ithenticate.com/plagiarism-detection-blog/bid/52974/Plagiarism-Punishment

However, it is safe to cite sources and mark it clearly in the Posts.

It would be good if the source is marked as ‘Source’ in the Post with a Link of the relevant material quoted.

This applies to images as well.

Quote as .image from or image source  the link of the web page from where you are using,

In some case you may get permission from the Authors to use them in your posts.

How many words or what percentage one may use from sources?

It is very delicate and depends on the nature of the Post, the word count of your Post.

It is safe to quote with source maximum 200 words in a Post of 800 words or roughly 25 % at the most.

So it is better to be original and wherever we feel necessary we may use other posts, material with citations, like marked as Source, with words from the source not exceeding 200 words in a Post of 800 words.

Lesser than this is ideal and this depends on your judgement.