Expressed Sequence Tags or ESTs, as the name suggests, are the new generation tools providing new dimension to transcriptome analysis. They are the tiny sequences of cistron randomly selected from genome library and can be used to identify and map the whole genome of any particular species. ESTs are usually 200 to 500 nucleotides long and are generated by sequencing the ends of DNA.
ESTs can be obtained without much expenditure and are quite fast in genomic analysis. The EST sequences can be used to search the homologous organisms in different databases such as NCBI (National Centre for Biotechnology Information). Thus we can collect information on expression patterns of different species. Therefore, they play vital role in discovery of gene and genome analysis