The N-terminus is a crucial part of a protein chain as it determines the folding and functionality of the entire molecule. There are several synonyms for this term, such as amino-terminal, the start of the polypeptide chain, or N-end. These words are used interchangeably in scientific literature and research papers. The N-terminal amino acid residue is the first amino acid in the protein sequence, and its properties influence the stability and activity of the protein. Therefore, researchers pay great attention to studying the N-terminus, and identifying its role in protein structure and function.