Questioned document analysis examines physical evidence from documents like handwriting, typewriting, photocopies, and ink to determine authenticity or identify forgeries. Characteristics like defects in typewriter parts or marks from printer components can be matched between documents. Security features in currency and documents include microprinting, security threads, and special inks. Forgeries are categorized as traced, simulated, freehand, or lifted depending on the method used. Handwriting analysis examines unique writing habits and patterns to determine authorship.