At the time of writing a manuscript we use lot of written material of some other paper and give that reference too. Des it comes under paraphrasing or plagiarism?
Paraphrasing is when you add your own interpretation of the text (the material) you use. You do not use word for word or even the majority of the work. When you paraphrase, it is primarily your own understanding of the work. You still need to reference the original source (s) you paraphrase. It is not a summary of the work, which is simply a condensation of the work.
A really great resource for understanding paraphrasing is available at the Online Writing Lab from Purdue University at:
Plagiarism is copying the work (s), word for word, and claiming it as your own without permission. It is illegal and unethical. Again, OWL has a great overview at:
Dear paraphrasing is using your own words provided the meaning of the write up is not lost and still cite the author you used his work and plagiarism is using people's work and fail to acknowledge the owner of the work by citing him and copying most of the work word to word most times instead of extracting the meaning and use your own understanding. It is good to paraphrase while writing.