Multiple sequence alignment
Multiple sequence alignments are of great interest because homologous sequences, although not necessarily having great similarity, often preserve similar structures and functions.
Introduction
One of the fundamental questions in biology is to know which proteins are related to another protein.
We can find some examples in this Venn diagram of orthologous sequences; which are similar because they have some common ancestor. Or, for example: cytochrome c (a protein found in mitochondria) from humans and mice.