This book explains the world of database systems to bioinformatics and cheminformatics database users. It begins with a survey of popular databases, including primary genetic and protein sequence, phylogenetic, structure and pathway, and microarray databases. The text discusses information management and modeling issues in these databases, addressing data quality issues as well as efforts in the data cleaning field to combat such problems. From drug discovery to the structure of various molecular components of the cell, the authors present new applications and case studies illustrating concepts in database systems.