The paper presents measurements of jet energy calibration and transverse momentum resolution in the CMS detector at the LHC, using data from proton-proton collisions at a center-of-mass energy of 7 TeV. The jet energy response and transverse momentum resolution are determined using dijet and $\gamma/Z+jets$ events. Three jet reconstruction methods are considered: calorimeter-based jets, Jet-Plus-Track jets, and Particle Flow jets. The jet energy calibration is performed using a factorized correction scheme, including offset correction, MC calibration, and residual corrections for relative and absolute energy scales. The jet transverse momentum resolution is measured using the dijet $p_T$-balancing method and the $\gamma/Z+$jet $p_T$-balancing method. The results show systematic uncertainties related to resolution bias and radiation imbalance, with the Particle Flow jets exhibiting the smallest uncertainties. The absolute jet energy response is measured using the Missing Transverse Energy Projection Fraction (MPF) method, which is less sensitive to biases compared to the $p_T$-balancing methods. The paper also discusses the systematic uncertainties associated with the jet energy calibration and resolution measurements.The paper presents measurements of jet energy calibration and transverse momentum resolution in the CMS detector at the LHC, using data from proton-proton collisions at a center-of-mass energy of 7 TeV. The jet energy response and transverse momentum resolution are determined using dijet and $\gamma/Z+jets$ events. Three jet reconstruction methods are considered: calorimeter-based jets, Jet-Plus-Track jets, and Particle Flow jets. The jet energy calibration is performed using a factorized correction scheme, including offset correction, MC calibration, and residual corrections for relative and absolute energy scales. The jet transverse momentum resolution is measured using the dijet $p_T$-balancing method and the $\gamma/Z+$jet $p_T$-balancing method. The results show systematic uncertainties related to resolution bias and radiation imbalance, with the Particle Flow jets exhibiting the smallest uncertainties. The absolute jet energy response is measured using the Missing Transverse Energy Projection Fraction (MPF) method, which is less sensitive to biases compared to the $p_T$-balancing methods. The paper also discusses the systematic uncertainties associated with the jet energy calibration and resolution measurements.