I firmly believe the best plagiarism checker is the human person who knows how to detect cheating. It is hard for one person to copy another person's writing style. Indicators of cheating are dramatic changes in syllabication, word choice, sentence structure and usage patterns. It is easy to detect plagiarism once the teacher is familiar with students' writing style differences. A skilled teacher is much better than machines or programs.
I had a student about 10 years ago turn in a paper on sports management. It was so far from that student's writing style that it did not take long for me to find the actual paper the student had copied from the internet which the student turned in as original work. The student was punished accordingly.
Turnitin seems to be the industry standard. It keeps developing regularly, adding to its range of tools (for both academic staff and students), and tries hard to to move it's anti-plagiarism ethos away from it being a 'checking tool' as a punitive means to 'find those that cheat'- more towards an assistive software programme that allows staff and students to improve their academic assignment/thesis-writing skills.
Just wanna share something about Turnitin, one of disadvantages is it cannot detects if someone reproduce the data in form of table and graphical image.
Thank you for your answer. Yes, those people should be punished. But, I have a different thought. Sometimes, it happens unintentionally. Even if 2-3 words in a sentence match to somebody else's published articles, all these software show the content is plagiarized. I have used turnitin, crosscheck and all. I believe all the top journals and conferences follow strictly this practice of checking the manuscript to ensure all the contents are not copied from any other sources. So, there is no question of doing that if you focus for top journals. By the way, as far as checking by faculties are concerned, I believe they focus more on technical and grammatical aspects. How can a faculty check those, where a software shows few percentage of plagiarism even if 2-3 words in a sentence matches with other resources. Don't you think it's impractical? Yes, from overall structure and content of the paper, you can judge to some extent if you know closely the talent and capability of your students.
I have found out that in turnitin some of the springer journals goes undetected. My own paper, already published in springer, when check with turnitin later showed 0% similarity.
I feel an unintentional act of sloppy editing is not cheating. Thus, I agree with you on that point.
Plagiarism to me is a willful act to deceive. Unintentional misrepresentation from sloppy editing or the inappropriate use of fully quoted terms without quotation marks or improper attributions of an original sources falls short of cheating or theft of another person's words. However, getting credit in an academic course in both cases is problematic.
There are a number of recent cases in the USA where journalists and a few Congressmen have been caught plagiarizing their articles and their speeches. Some were proved intentional while some were not.