DNA-chip analysis has come a long way since the first conference in Moscow in 1991. Nowadays, DNA-microarrays seem to be a common commodity in biological sciences. The complexity hidden behind the apparent ease of such studies, however, is highlighted by the fact that it took about ten years before the methodology really set off. Also, on closer scrutiny, one realises that some problems still remain. Nevertheless, microarrays produce data on a scale beyond imagination a few years ago.The authors of the book took part in bringing this about. They are well-known experts in the field, many - like Edwin Southern, Hans Lehrach, Radoje Drmanac, Pavel Pevzner and Charles Cantor - have been actively pursuing array technology for more than a decade. They demonstrate the continuous development in both technology and application areas and elucidate on critical points that need to be considered when performing microarray analyses.