The book "Purple Cow: Transform Your Business by Being Remarkable" by Seth Godin is about the importance of standing out in a crowded marketplace. Godin argues that in today's competitive world, being average or just slightly better than your competitors is not enough. To truly succeed, businesses need to be remarkable, like a purple cow in a field of brown cows. The book explores various strategies and examples of how businesses can differentiate themselves and create remarkable products, services, and marketing campaigns to attract attention and build a loyal customer base.