This document discusses factors that affect chemical shift in NMR spectroscopy. There are four main factors: electronegativity of nearby atoms, hybridization, magnetic anisotropy effects from pi bonds, and hydrogen bonding. Electronegative atoms and groups cause deshielding and shift signals downfield. S-character hybridization also causes deshielding. Magnetic fields from pi electrons shift aromatic protons upfield between 7-8 ppm, vinyl protons between 5-6 ppm, and acetylene protons around 2.5 ppm. Hydrogen bonding lengthens bonds and shifts protons downfield, with effects ranging from 0.5 ppm to 5 ppm depending on bonding strength. Carboxylic acid protons experience strong hydrogen bonding