The ''post-genomics'' era has given rise to a range of web-based tools and software to compile, organize, and deliver large amounts of primary sequence information, as well as protein structures, gene annotations, sequence alignments, and other common bioinformatics tasks. In general, there exist three types of databases and service providers. The first one includes the popular public-domain or open-access databases supported by funding and grants such as NCBI, ExPASy, Ensembl, and PDB, Many public databases are already extensively links so that complementary information in another database is easily accessible; for example, Greenback and the PDB are closely intertwined. However, specialized tools organized and hosted by specific research groups can be difficult to integrate into this linkage effort because they are narrowly focused, are frequently modified, or use custom versions of common file formats. Advantages of sequence profiling tools include the ability to use multiple of these specialized tools in a single query and present the output with a common file formats. Advantages of sequence profiling tools include the ability to use multiple of these specialized tools in a single query and present the output with a common Interface, the ability to direct the output of one set of tools or database searches into the input of another, and the capacity to disseminate hosting and compilation obligations to a network of research groups and institutions rather than a single centralized repository. This approach will provide a solid foundation this subject on which the student will continue to build during the remainder of his or her professional life and most certainly during the remainder of his or her professional education.