Sequence alignment is trying to match a DNA or amino acid sequence, even though the sequences might not be exactly the same, otherwise it would be a straight up string-search algorithm.
This is fundamental in bioinformatics for two reasons:
BLAST is a sequence alignment.
The NCBI free-to-use BLAST server: Having a centralized query server is fundamental, because the gain of sequence alignment really comes from having one huge database to link information together, which is best centralized.