The study of adsorption kinetics provides significant insight into the rate at which solutes are adsorbed and the duration of adsorbate interaction at the solid–liquid interface. Similarly, adsorption isotherms are fundamental to understanding the interaction dynamics between adsorbates and adsorbents and to determining the maximum adsorption capacity of the adsorbent. Thermodynamic analyses serve to complement these studies by evaluating the feasibility, spontaneity, and energy changes involved in the adsorption process. This article presents an overview of the main models of adsorption kinetics, isotherms, and thermodynamics, as well as their optimization and validation. The models of adsorption kinetics reviewed in this article include the pseudo-first-order, pseudo-second order, Elovich and intra-particular diffusion models. These models are based on the assumption of heterogeneous reactions at the solid–liquid interface. The linearised forms of these equations facilitate the calculation of important parameters, including adsorption capacity, rate constants, adsorption rates, and intraparticle diffusion coefficients, using the slopes and intercepts derived from graphical representations. Optimization and validation of these models are performed using statistical metrics such as the coefficient of determination (R2), sum of squared errors (SSE), and residual root mean square error (RMSE) to ensure the reliability of the models in describing adsorption behavior. Isotherm models review include Langmuir, Freundlich, Temkin, Redlich-Peterson, and Dubinin-Radushkevich. These models provide insight into the following aspects of adsorption: affinity, mean free energy, and the nature of the adsorption process, including whether it involves physisorption or chemisorption, and whether it occurs in single or multi-layer adsorption. Furthermore, thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) are discussed, as they provide crucial details about the spontaneity, feasibility, and energy profile of the adsorption process. The values and signs of these parameters indicate whether the adsorption is exothermic or endothermic, thus providing deeper insights into the energetic aspects of the system. This review of adsorption kinetics, isotherms, and thermodynamics and the optimization and validation of adsorption models provides a solid basis for the understanding and optimizing of the adsorption process in a wide variety of applications.