串行比对指将两个或多个串行排列在一起，标明其相似之处。串行中可以插入间隔（通常用短横线“-”表示）。对应的相同或相似的符号（在核酸中是A, T(或U), C, G，在蛋白质中是氨基酸残基的单字母表示）排列在同一列上。

这一方法常用于研究由共同祖先进化而来的串行，特别是如蛋白质串行或DNA串行等生物串行。在比对中，错配与突变相应，而空位与插入或缺失对应。串行比对还可用于语言进化或文本间相似性之类的研究。

术语“串行比对”也指构建上述比对或在潜在的不相关串行的数据库中寻找significant alignments。

In bioinformatics, a sequence alignment is a way of arranging the sequences of DNA, RNA, or protein to identify regions of similarity that may be a consequence of functional, structural, or evolutionary relationships between the sequences. Aligned sequences of nucleotide or amino acid residues are typically represented as rows within a matrix. Gaps are inserted between the residues so that identical or similar characters are aligned in successive columns. Sequence alignments are also used for non-biological sequences, such as calculating the edit distance cost between strings in a natural language or in financial data.