BLAST, acronym for "Basic Local Alignment Search Tool", is a local sequence alignment search method based on a modified form of Smith-Waterman algorithm ([]). It was first described in 1990 by Altschul et al ([1]). NCBI started providing sequence alignment service to the public using BLAST in 1992 through its blast email server. This service was superseded by a web server in 1997. Currently NCBI BLAST web server is the major venue for NCBI to delivery sequence alignment services to the public, which processes between 200,000 to 300,000 search requests per day.
Over the years, NCBI had introduced various new programs based in this algorithm, such as PSI-BLAST, MEGABLAST, and rpsblast, to address the needs in various genome and protein domain analyses. The term BLAST now commonly refers to this collection of programs from NCBI that are based on the same heuristics. These programs along with the accessory tools are combined into a single binary package and made available to the public through NCBI ftp blast ftp site at:
ftp://ftp.ncbi.nih.gov/blast/executables/.
Despite this great expansion, blastall - the original program with enhanced-features, remains as the core of the BLAST package.