Ion exchange chromatography is a technique used to separate charged molecules like proteins, peptides, amino acids, and nucleotides. It works by exchanging ions between a stationary ion exchange resin and a mobile phase liquid. There are two main types of ion exchange resins - cation exchangers that attract positively charged ions, and anion exchangers that attract negatively charged ions. Ion exchange chromatography is useful for purifying solutions, extracting enzymes, softening water, and separating molecules like sugars, amino acids, and proteins.