One of the problems with online content is that unscrupulous content providers and bloggers simply scrape content from other people. This type of plagiarism is enough to get an entire site dropped by its host, but it first has to be detected.
There are a few good, low-cost or free plagiarism detection sites that can report in seconds if a piece of content has been stolen and where where that content has been republished. One of the sites also offers continuous monitoring of a site and reports any plagiarism.
Article Checker
Article Checker is a free way to quickly check text of any size for duplicate phrases. It's a little sensitive, and tends to bring up common phrases that aren't necessarily plagiarized. But, Article Checker allows anyone to paste content into a box and to check it quickly and for free. There is no registration required. There is also the option of checking through Google for duplicates, Yahoo or through both at the same time.
Article Checker also has a feature that allows users to enter a url and to see how many phrases on the site can be found elsewhere online. This feature is also extremely sensitive, and it does not show where the phrases can be found.
CopyScape
CopyScape is well-known for its fast, accurate searches, and it's not sensitive enough to pick up small, common phrases. Users can check a url for plagiarized content for free. The site will also show users the locations of the plagiarized content.
To be able to copy and paste text straight into the site for a plagiarism check, the site charges a fee. With CopyScape Premium, users buy blocks of searches that are .05 apiece and are good for one year.
CopySentry is CopyScape's paid service that continually monitors a site to catch plagiarism of that site. If any plagiarized content is published online, CopySentry emails the owner of the original content and informs them.
PlagiarismDetect
PlagiarismDetect is a newer site, but it offers free plagiarism detection for text searches. The site was created for college students who want to ensure that their papers can not be accused of any plagiarism, but it can be used for online content just as easily. PlagiarismDetect requires registering for a free account.
Penalties for plagiarism can include having a site closed down, being fired from a writing or advertising job or failing a high school or college paper. The legal penalties for plagiarism can include costly settlements and the forfeiture of the profits made from plagiarized materials. Becoming familiar with the Fair Use Doctrine can make avoiding plagiarism easier.