Purple cow is a marketing concept developed by marketer and entrepreneur Seth Godin. Please explain.
The following is a definition of the concept of "Purple Cow" gained from Wikipedia:
Purple Cow: Transform Your Business by Being Remarkable is a book by Seth Godin. The book presents Godin's personal belief that creative advertising is less effective today because of clutter and advertising avoidance. The book advocates that companies produce remarkable products and target people who are likely to spread word of mouth about the product. USA Today said it "remind business people of the tried-and-true path to success: Make a great product". 
Within this concept, Mr. Godin refers to the concept that advertising, per se, has become boring and unremarkable --- often times wasted in the sheer volume and attempts to exploit, rather than educate, the target audience.
Instead, Mr. Godin suggests that firms should be more interested, and provide a higher priority to providing "remarkable" products and services. Think of all of the advertising that is thrown at us daily --- every time we access a web page on the internet, every time we open a magazine, every time we ...
A summary of the PURPLE COW concept established by noted author Seth Godin.