Comparative genomics is a field that uses genome sequence comparisons to understand the functional aspects of genetic information. While a complete genome sequence provides the DNA sequence, it does not directly explain how this information leads to observable traits. Comparative genomics aims to identify conserved and functional regions of the genome, which can improve health and society. The principles of comparative genomics involve identifying conserved DNA sequences that are inherited from a common ancestor and those that regulate gene expression in related species. Differences between species are often found in sequences that encode or control proteins and RNAs responsible for species-specific traits. Comparative genomics can address different questions depending on the phylogenetic distance between species. At long distances, it helps identify conserved genes and their functions, while at moderate distances, it reveals functional and nonfunctional DNA. At very close distances, such as between humans and chimpanzees, it can identify key sequence differences under positive selection. Alignment of DNA sequences is central to comparative genomics, but computational challenges limit the ability to align large genomic regions. Precomputed alignments are available through various databases and tools. Comparative genomics has provided insights into genome evolution, including the conservation of gene order and synteny, the identification of functional DNA regions, and the role of segmental duplications in genomic diversity. It also aids in predicting gene functions and identifying regulatory elements. The analysis of genome sequences has revealed that a significant portion of the human genome is under purifying selection, indicating functional importance. However, challenges remain in accurately predicting the function of noncoding sequences. The future of comparative genomics involves integrating data from multiple species to enhance functional predictions and understanding of genome evolution. Advances in computational methods and the availability of more genome sequences will further improve the accuracy and scope of comparative genomics.Comparative genomics is a field that uses genome sequence comparisons to understand the functional aspects of genetic information. While a complete genome sequence provides the DNA sequence, it does not directly explain how this information leads to observable traits. Comparative genomics aims to identify conserved and functional regions of the genome, which can improve health and society. The principles of comparative genomics involve identifying conserved DNA sequences that are inherited from a common ancestor and those that regulate gene expression in related species. Differences between species are often found in sequences that encode or control proteins and RNAs responsible for species-specific traits. Comparative genomics can address different questions depending on the phylogenetic distance between species. At long distances, it helps identify conserved genes and their functions, while at moderate distances, it reveals functional and nonfunctional DNA. At very close distances, such as between humans and chimpanzees, it can identify key sequence differences under positive selection. Alignment of DNA sequences is central to comparative genomics, but computational challenges limit the ability to align large genomic regions. Precomputed alignments are available through various databases and tools. Comparative genomics has provided insights into genome evolution, including the conservation of gene order and synteny, the identification of functional DNA regions, and the role of segmental duplications in genomic diversity. It also aids in predicting gene functions and identifying regulatory elements. The analysis of genome sequences has revealed that a significant portion of the human genome is under purifying selection, indicating functional importance. However, challenges remain in accurately predicting the function of noncoding sequences. The future of comparative genomics involves integrating data from multiple species to enhance functional predictions and understanding of genome evolution. Advances in computational methods and the availability of more genome sequences will further improve the accuracy and scope of comparative genomics.