Membrane separation processes are the most important type of separation by mass transfer within a single phase. In these processes, the membrane, a thin layer that selectively separates components of a liquid and controls mass transfer between phases, enables the separation of substances. Depending on the driving force of the process and the size of the components, various membrane processes are defined, with the dialysis membrane process being one of the most significant, primarily used in hemodialysis. Membranes are classified into two groups: cellulose membranes and those made from synthetic polymers. Advances in polymer chemistry have led to the development of membranes with special properties, which necessitate an overview of their classification and benefits. The creation of high-performance and more efficient membranes, such as those used in hemodiafiltration, has resulted in improved removal rates of uremic toxins. Additionally, new membranes with larger pores have been developed for specific therapies, allowing the removal of higher molecular weight molecules such as inflammatory mediators and immunoglobulin light chains in conditions like multiple myeloma. Parameters such as new permeability indices, hydrophilic or hydrophobic properties, absorption capacity, and electrical potential have been described for these membranes. Consequently, the structures of these membranes were studied to enhance waste removal efficiency, prevent the removal of beneficial blood components, improve compatibility with the blood environment during hemodialysis, and enable faster separation processes to reduce the duration of hemodialysis and minimize side effects.