One of the first things I noticed when I first came aboard here on Steemit is the active effort of the community to promote original content, and actively seek and call out any members who might have committed plagiarism. The daily log of @cheetah and @steemcleaners can give us a glimpse of the problem the Steemit community have to tackle in terms of plagiarized contents. Conversely, write-ups about complaint to @cheetah and @steemcleaners have also been numerous. But I believe most users are not really unaware about plagiarism, it is one of the things we were all carefully reminded of before we all started our journey as Steemians after all. Yesterday I read this write-up by @lebron2016 wherein she presented the basic tenets of paraphrasing. I write this entry in support of her initiative and would try to further clarify the importance of paraphrasing as well as give some tips on when one could do away with citing a source, and more importantly, when citing a source is a must.
What is paraphrasing?
My Merriam-Webster phone app answers this question quite shortly; paraphrasing is simply saying something, which you got from a source, with your own words (emphasis mine).

Screenshot from my phone (© 2017 Merriam-Webster, Inc.)
When should I paraphrase?
The simple answer is always. Unless you are quoting your source, you should always paraphrase. This rule always hold whether you cite your source or not.

Image taken from http://minds-in-bloom.com (©2014 Rachel Lynette, www. rachel-lynette.com)
When am I allowed not to cite my source?
You can be allowed not to cite your source if you have the following contents: general knowledge (this is tricky, read more below!), sharing your personal experience, and stating your personal opinion.
As you may have noticed, perhaps the majority of the most popular contents here on Steemit, and generally in the internet, are travel blogs and sharing photos with the photographer's description. As such entries come from personal experience and perspective, the authors are not required to cite their source, for they are the source. Sharing one's own opinion is also forgiven, but you should be able discern the difference between an opinion and an informed opinion. Informed opinion is usually an amalgam of different ideas and concepts from a lot of sources, thus people who give out such opinion also mention their sources as a means to justify their conclusion.
But always give credit where it is due.
I mentioned that travel blogs and photograph sharing are unique ways you can share your content without being bugged to give out your source, but in reality, when you do travel for the experience and/or take your photos, you would meet people who would actually give out the bits and pieces which would make it into your entry. Mentioning them is the least you can do for them. If you look at the contents authored by well-known Steemians like @sweetsssj and @timsaid, they instinctively describe their experience and mention people (and animals^^) they meet along the way. While prolific writers such as @stellabelle and @surpassinggoogle give credit to other people about where they got an idea from in their informative and motivational entries. @surpassinggoogle even makes his own quotable quotes! By contrast, @jerrybanfield outright mention the people who help put up his entries in the beginning, even going as far as giving the liquid payout of his posts the the ones who helped him greatly, such as @lexiconical and others. If you have read Dr. Stephen R. Covey's The Seven Habits of Highly Effective People, @jerrybanfield fully utilizes the 6th habit which is to Synergize. To put synergy in an equational context, 1 + 1 is equal to more than 2!
When should I cite my source/s?
My answer is: as much as you can. I said above that you may be forgiven in presenting a general knowledge without citing a source, but that depends in level of knowledge you are presenting. For example when I say Jose Rizal is the National Hero of the Philippines, normally, I would not expect anyone to call me out on this since it is essentially a public knowledge. To make it safe, I will just say: Jose Rizal is the National Hero of the Philippines based on the official recommendation of the Philippine National Heroes Committee in 1995 by virtue of Executive Order No. 75, declared by former Philippine President Fidel V. Ramos, and arguments put forward by the renowned Philippine historian Ambeth R. Ocampo. But if I say, Jose Rizal hooked up with a lot of women, then you should normally ask me: "How can you make such a claim? Did you know him in person? Talked to anyone who personally know him? Did you live through his time?". Even if it may be a public knowledge in itself, I cannot make such statement without citing a source. So instead, the more acceptable way of saying such claim would be: Jose Rizal hooked up with a lot of women based on the autobiographical work by Leon Ma. Guerrero entitled The First Filipino (1963). Of course you can also research some other autobiographical works, including Rizal's own correspondence with his mentor and friend, Ferdinand Blumentritt.
Writing about personal experience and personal knowledge would also sometimes require an author to cite some sources (read informed opinion above). For instance, consider this entry by @gorgeousdindi. In it, she said that Purple colored Rose Mallow is rare. Rose Mallow is known in the Philippines as Gumamela. Obviously she was sharing based on her personal experience and perspective. I even concurred based on my own personal experience and perspective too. However, if I try to quantify my claim (or she on hers), like when I say that only 3% of Rose Rose Mallow flowers are colored purple, then I would need to provide a source for such a claim. But I didn't, because I didn't find a source pertaining to the ratio of purple Rose Mallow flowers as compared to the other colors (if you found a possible source, please link it below, I'm interested to know 😉).
It depends on the context.
As I commented in @lebron2016's write-up: "There are ideas, data, and/or facts that are quite uncommon or even rare, so one should cite the source on top of paraphrasing when writing such content based on them. An excellent example of this is research results", and of course, copyrighted literary works. My forte is more on research, so I would share more about it. One cannot merely paraphrase a research write-up without properly citing it as a source. This is especially true if the research in question is proprietary (i.e. a research result leading to a discovery of a new drug, or a published clinical study of a new medical equipment by a certain company). Plagiarism is easy to spot when it comes to these cases especially if you're not part of the research team itself, or someone competent enough to explain the intricacies of the source material. For example, if you are not a marine scientist with specialization in Cetacean studies, how can I expect you to be able to write and explain the role of dolphins in marine ecology and their influence in other phelagic species without even citing one significant source?
Granted, parallel thinking and parallel studies/experiments does happen. In such cases, sometimes the authors or teams can talk it out, assuming both started their work independently. Most of the time, the credit goes to the first one who could file for patent, or the first one to publish their work. There are also some who take the industrial secret approach, which makes their products vulnerable to reverse-engineering, but that is another topic altogether! Whatever the case is, laboratories and research institutes usually keep their raw data logs secured, and even authors keep their drafts, just in case someone tries to sabotage their work, copy it, and pass it as their own. So be careful in copying someone else's work!
It all boils down to respect.
Paraphrasing and citing your sources may sound a pain in the ass for some people, but just look at it this way: if you worked hard for something, you would not want anyone to take credit for your work and profit from it, do you? Unless you worked for it with charity in mind. So respect others' hard work and cite them! After all you became a little bit more competent based on what you learned from them. Is it not enough?.
If you would like to learn more about paraphrasing and source citation, google more about the topic. I suggest you start with this article: https://www.princeton.edu/pr/pub/integrity/pages/cite/.

