Paper chromatography is a physical technique used to separate and analyze components in mixtures. It works by partitioning components between a stationary phase (paper) and mobile phase (solvent). Key steps include spotting the sample, developing the chromatogram by allowing the mobile phase to travel up the paper, drying the paper, and analyzing the separated components. Paper chromatography is useful for separating and identifying various substances like amino acids, drugs, and organic compounds. It has applications in fields like pharmacy, biochemistry, and research due to being inexpensive and easy to perform.