Urban expansion and extending road networks to cover larger areas consume many natural resources, as they need aggregate from quarries and bitumen in the case of flexible pavement or cement in the case of rigid pavement. Bitumen extraction is difficult due to the complexity of its extraction process and the consumption of a large amount of oil. This is in addition to the environmental damage, whether from the manufacture of bitumen or cement. In recent years, all countries have been interested in sustainability and preserving natural resources. So, research has been directed to study how to take advantage of the waste and recycle it in engineering. RAP is among the most important wastes, as many studies have been conducted to reuse it in engineering applications, whether pavement or concrete. This research sheds light on RAP based on previous researches, from obtaining it to reusing it. RAP can be used in the road field by partially or completely replacing the new asphalt mixture. To ensure the revitalization of the rap, rejuvenating agents are added during the mixing process. Studies have indicated that using RAP in pavement has 4 different techniques: HMIR, HIR, CIR, and FDR. As for the results of its use in pavement application, it was found to reduce rack resistance, fatigue life, shear strength of soil, and CBR of soil. On the contrary, it increases the resistance modulus and decreases the rutting. In concrete applications, RAP decreases the workability, compressive strength, flexural strength, and indirect tensile strength; on the contrary, it increases the toughness of concrete.