Protein markers, also known as molecular weight markers or ladders, are essential consumables used in gel electrophoresis to estimate the size of proteins in a sample. These markers contain a mixture of proteins with known molecular weights, which migrate through the gel alongside the experimental samples. After electrophoresis and staining, the protein markers appear as distinct bands that serve as a reference for determining the molecular weight of unknown proteins in the gel. Protein markers are available in pre-stained, unstained, or fluorescent formats, providing flexibility for visualisation and analysis. These tools are crucial in molecular biology, biochemistry, and proteomics, ensuring accurate protein identification and analysis in research involving protein expression, purification, or modification studies.