Hexa-His (HHHHHH) is widely used in biochemistry and molecular biology for protein purification and detection. Its primary application is in affinity chromatography, where it serves as a tag to facilitate the isolation of recombinant proteins. The six consecutive histidine residues bind strongly to immobilized metal ions, such as nickel or cobalt, on chromatography columns, enabling efficient purification of tagged proteins. This method is highly specific, scalable, and compatible with a variety of protein types. Additionally, Hexa-His tags are utilized in protein detection techniques like Western blotting, where anti-His antibodies are employed to identify and quantify tagged proteins. The tag’s small size minimizes interference with protein structure and function, making it a versatile tool in research and industrial protein production.