Multiple sequence alignment is the alignment of multiple biological sequences (such as DNA, RNA or protein sequences) to identify similarities and differences between them. This kind of alignment helps to understand the evolutionary relationship of biological sequences, the conservation and variability of functional domains. Multiple sequence alignment can be achieved through a variety of methods, such as ClustalW, MAFFT, Muscle, etc. This plays an important role in bioinformatics, genomics and systems biology research, providing a key analytical tool for studying gene families, evolutionary relationships and functional domains.