This volume collects the contributions of most of the lecturers al BOSS’99, the 2nd Bologna Summer School on Biotechnology held in Bologna on October 10-16, 1999. In the genomic era (or post-genomic era, after human genome sequencing has benn almost completed) DNA sequencing is increasing our knowledge of the molecolar structure of genetic codes fram bacteria to man at a hyperbolic rate. Billions of nucleotides and millions of aminoacids are already filling the electronic files of the data bases presently available, which contain tremendous amount of information on the most biologically relevant macromolecules, such as DNA, RNA and proteins. The crucial question is how the select the relevant pieces of information in order to focus the researh activity on tractable problems. Intelligent tools are therefore needed to optimise the search. Data mining for sequence analysis in biotechnology has been substantially aided by the development of new powerful methods borrowed from the machine learning approach and described in this book.