 Dear students, in this model, I will continue building on BLAST. So as you would remember, BLAST is an online search tool to compare nucleotide or amino acid sequences from databases. So to start with, the Smith-Waterman or even the Needleman Munch can help you to compare and align sequences. But given that there are so many sequences that you need to compare and align, it is a very slow process. So BLAST helps you to do it in a fast and brisk manner. The way it shortens its runtime is by making approximate matches. So by making approximate matches, it is creating a compromise between the accuracy and the search time. So the accuracy actually drops while the runtime becomes faster. So essentially BLAST provides for an approximate sequence matching and scoring. More so, to start with using BLAST, the input to the BLAST algorithm that is available online comprises of faster sequences or protein or nucleotide IDs. So once you input this information in these formats, then you can run the BLAST provided you have specified the search parameters. So once you have completed the search using BLAST, the output from the software can be in multiple formats. It can be either in plain text or HTML or XML. So for a better visualization, BLAST also provides a tabulated search result in which you can click on various results and the alignments to see the results and their quality. So to start with the input to BLAST comprises of gene IDs. That is if you are interested in searching the nucleotide sequences, you can simply go to gene bank that is available here. You can select nucleotide and then you can also select protein IDs for the protein BLAST. If you remember there are multiple types of BLAST, the nucleotide BLAST, the protein BLAST and several others. So this is the protein BLAST. So you just need the protein IDs. Where do you get these protein IDs? You simply go to Uniprot and you search for various proteomes and get the protein IDs. So once you input the gene or protein ID or the gene or protein sequence, then you can BLAST it against the database of your choice and receive the search. The results will look like this as shown here. So you can have your query sequence listed in red and you can have the matching proteins or nucleotides that are here presented like that. Of course the tabulated scores are also provided along with their E-values that is the statistical evaluation and this can be a long list depending on the number of matches that have been made. So in conclusion, the purpose of BLAST is to compare these biological sequences that you have in a very brisk way. Remember that not all nucleotide or protein sequences are known to us. So if you sequence a gene or a protein from your wet lab experiment, then you can bring that sequence into the BLAST software and find out which other already reported genes or proteins have similar sequences. So this can be very useful in evaluating information like evolutionary origin as well as the function of the protein or gene. So the inputs and outputs as I just mentioned are simply gene IDs or protein IDs or the sequences and the output is in the form of tabulated HTML or XML formats. More so, we would like to know how the BLAST software works because it is important to know why your results have a score like that.