This literature review examines the impact of parent concrete strength on the characteristics of Recycled Concrete Aggregates (RCAs) and Recycled Aggregate Concrete (RAC). The review highlights that the porosity of the source concrete and the crushing procedure of the aggregates are the main causes of variability in RCA characteristics. Contrary to the common belief that RACs have lower quality than conventional concrete, studies show that RCAs produced with aggregates from high-strength concrete (not less than 80 MPa) can have equivalent or better properties compared to natural aggregate concrete. The review identifies limitations in previous studies and provides recommendations for future research, emphasizing the need to understand the interaction between parent concrete strength and RCA/RAC properties. The review also discusses the physical, mechanical, and long-term attributes of RCAs and RACs, including water absorption, specific gravity, compressive strength, elastic modulus, tensile strength, flexural strength, durability, and microstructure. The findings suggest that the quality of RCAs and RACs can be improved by carefully considering the source concrete strength and the crushing process.This literature review examines the impact of parent concrete strength on the characteristics of Recycled Concrete Aggregates (RCAs) and Recycled Aggregate Concrete (RAC). The review highlights that the porosity of the source concrete and the crushing procedure of the aggregates are the main causes of variability in RCA characteristics. Contrary to the common belief that RACs have lower quality than conventional concrete, studies show that RCAs produced with aggregates from high-strength concrete (not less than 80 MPa) can have equivalent or better properties compared to natural aggregate concrete. The review identifies limitations in previous studies and provides recommendations for future research, emphasizing the need to understand the interaction between parent concrete strength and RCA/RAC properties. The review also discusses the physical, mechanical, and long-term attributes of RCAs and RACs, including water absorption, specific gravity, compressive strength, elastic modulus, tensile strength, flexural strength, durability, and microstructure. The findings suggest that the quality of RCAs and RACs can be improved by carefully considering the source concrete strength and the crushing process.