Machine learning is one of the older areas of artificial intelligence and concerns the study of
computational methods for the discovery of new knowledge and for the management of
existing knowledge. Machine learning methods have been applied to various application
domains. However, in the few last years due to various technological advances and research
efforts (e.g. completion of the Human Genome Project, evolution of the Web), new data have
been available and consequently new domains where machine learning can be applied have
been arisen. Some of these modern applications are learning from biological sequences,
learning from email data, and learning in complex environments such as Web. three application
domains as well as some recent efforts, where machine learning techniques are applied in order
to analyze the data provided by these domains.