There are many books covering Fibonacci from an artistic and historical point of view and almost as many suggesting that Fibonacci retracements and numbers can be successfully applied to financial market time series. What is missing is a book that addresses the common errors in using screen based Fibonacci (and Gann and other tools). The book is a critical exploration of Fibonacci numbers, retracements, projections, timeframes and fanlines and their current usage within the financial markets by technical analysts. Although they can be extremely effective analytical tools when used appropriately, mistakes in usage can be extremely costly from a financial and credibility viewpoint. George MacLean takes a brief look at the history of Fibonacci and Gann, before providing a full account of their applications in financial markets, including fixed income, equity, foreign exchange, commodities and indexes. In particular, he draws attention to the overuse and misuse of easily applied computer packages available to professional and amateur traders.