In the post-Human Genome Project era, awareness of the resources available through the internet is essential to both molecular biologists and clinicians. An overview of the main databases and analytical tools described in this chapter is important to understand the principles upon which hypotheses are generated, experiments are based and conclusions reached. Similarly, an introduction to the terminology of these resources often facilitates their use and adoption into practice. This chapter covers database resources such as NCBI/ Entrez, Ensembl and UCSC as well as analytical tools for sequence alignment, promoter analysis and molecular interactions.