Homologous recombination (HR) is a critical DNA repair pathway that repairs DNA double-strand breaks (DSBs) and interstrand crosslinks (ICLs), and supports DNA replication during replication fork stalling or breakage. HR involves the Rad51 protein, which forms a presynaptic filament to facilitate homology search and DNA strand invasion. This process is supported by context-specific factors, such as Rad52, which helps in DNA strand invasion and second-end capture. HR is essential for maintaining genomic stability and preventing cancer, as mutations in BRCA2, a key HR protein, are linked to breast and ovarian cancer and Fanconi anemia. HR also plays a role in DNA-based cancer therapies that induce DNA lesions, which are substrates for HR pathways. HR is divided into three stages: presynapsis, synapsis, and postsynapsis. During presynapsis, DSB ends are processed to form a 3'-OH single-stranded tail. Synapsis involves DNA strand invasion by the Rad51-ssDNA filament, leading to the formation of a D-loop. Postsynapsis includes pathways such as synthesis-dependent strand annealing (SDSA), break-induced replication (BIR), and double-strand break repair (DSBR). These pathways differ in their mechanisms and outcomes, with SDSA and BIR leading to non-crossover products, while DSBR can produce crossover products. HR is also crucial for repairing stalled or broken replication forks. Rad51 filaments are formed on RPA-coated ssDNA, and factors like Rad55-Rad57 and Rad52 are essential for this process. BRCA2, a key mediator in HR, is involved in both HR and Fanconi anemia (FA), a disorder characterized by defects in ICL repair. The FA pathway, which is critical for ICL repair in humans but absent in yeast, involves proteins such as FANCM, FAAP24, FANCZ, and FANCD1 (BRCA2). These proteins interact with DNA and are involved in the repair of ICLs through various mechanisms, including the processing of stalled replication forks. In conclusion, HR is a complex and essential pathway for DNA repair and replication, playing a critical role in maintaining genomic stability and preventing cancer. The interplay between HR and other DNA repair pathways, such as non-homologous end-joining (NHEJ) and translesion synthesis (TLS), highlights the importance of context-specific factors in processing DNA damage. Understanding the mechanisms of HR and its role in DNA repair is crucial for developing therapeutic strategies for cancer and other diseases associated with genomic instability.Homologous recombination (HR) is a critical DNA repair pathway that repairs DNA double-strand breaks (DSBs) and interstrand crosslinks (ICLs), and supports DNA replication during replication fork stalling or breakage. HR involves the Rad51 protein, which forms a presynaptic filament to facilitate homology search and DNA strand invasion. This process is supported by context-specific factors, such as Rad52, which helps in DNA strand invasion and second-end capture. HR is essential for maintaining genomic stability and preventing cancer, as mutations in BRCA2, a key HR protein, are linked to breast and ovarian cancer and Fanconi anemia. HR also plays a role in DNA-based cancer therapies that induce DNA lesions, which are substrates for HR pathways. HR is divided into three stages: presynapsis, synapsis, and postsynapsis. During presynapsis, DSB ends are processed to form a 3'-OH single-stranded tail. Synapsis involves DNA strand invasion by the Rad51-ssDNA filament, leading to the formation of a D-loop. Postsynapsis includes pathways such as synthesis-dependent strand annealing (SDSA), break-induced replication (BIR), and double-strand break repair (DSBR). These pathways differ in their mechanisms and outcomes, with SDSA and BIR leading to non-crossover products, while DSBR can produce crossover products. HR is also crucial for repairing stalled or broken replication forks. Rad51 filaments are formed on RPA-coated ssDNA, and factors like Rad55-Rad57 and Rad52 are essential for this process. BRCA2, a key mediator in HR, is involved in both HR and Fanconi anemia (FA), a disorder characterized by defects in ICL repair. The FA pathway, which is critical for ICL repair in humans but absent in yeast, involves proteins such as FANCM, FAAP24, FANCZ, and FANCD1 (BRCA2). These proteins interact with DNA and are involved in the repair of ICLs through various mechanisms, including the processing of stalled replication forks. In conclusion, HR is a complex and essential pathway for DNA repair and replication, playing a critical role in maintaining genomic stability and preventing cancer. The interplay between HR and other DNA repair pathways, such as non-homologous end-joining (NHEJ) and translesion synthesis (TLS), highlights the importance of context-specific factors in processing DNA damage. Understanding the mechanisms of HR and its role in DNA repair is crucial for developing therapeutic strategies for cancer and other diseases associated with genomic instability.