Private Label Rights (PLR) is the variation of Private Label brand concept, which is extended to written text. Private label products or services are typically those manufactured or provided by one company for offer under another company’s brand. The famous examples of Private Label are Wal-Mart brands, as the lower-cost alternatives to name brand products.
Private Label Rights allow you to change anything about the written text (labeled with that kind of rights), so that you effectively make it your own work. This is the similar concept to Ghost Writing, accept it is not a custom to re-write something that professional writer did for you. PLR is very actual these days, because the rise of the importance of blog posts, as well as any kind of large content base for search engine positioning.
Several years ago there was a massive appearance of PLR services, specially after the blog revolution in 2005. The main characteristic of those services is low price (comparing to price of professionally written texts, used for publishing), and not so good in quality. During 2006, because of a large competition, there were some good PLR services reported.
Although those texts are sometimes used for the base or inspiration to own articles (this is the recommendation), many people use PLR articles with the optimized keywords (key phrases) for their targeted groups (this is relatively OK). Of course, some people use those texts ‘as-is’, but Google makes it clear in its webmaster guidelines that it doesn’t like duplicate content.
PLR as the questionable online business model
The main question about the implementation of PLR articles is if they are used for a time optimization, you still loose the time to re-write (or optimize) texts. Search engines like original texts, and PLR articles can be in that category, only if they are modified enough.
It is indicative that if you search for the “private label rights” on several search engines, in first 100 results there is maybe one or two reputable sources (tip: you can use SEO Quake Firefox plug-in in Google Search results) who mention this online business model (or content creation tactic, one will say). Some of those ‘reputable’ sources uses the PLR article(s) to promote some affiliate programs from that ‘industry’.
My advice is NOT TO USE PLR articles, if you do not have a need, because it is better to pay little more (or not so little more) to have UNIQUE and ORIGINAL online content. If the right content is in the context of your users needs… The results have to be inevitable.