Metagenomics not only focuses on individual microorganisms, but also studies the entire microbial community in a specific habitat as a whole. This means that we can obtain genetic information of all microorganisms in the environment, not just those that can be cultured under laboratory conditions. Extract DNA directly from environmental samples and then use high-throughput sequencing technology to sequence these DNAs. Through this method, we can obtain a large amount of genetic information to analyze the composition, structure, and function of microbial communities. It can help us understand the microbial community structure in different environments, thereby revealing the relationship between microorganisms and the environment. In the field of medicine, metagenomics can help us study the microbial community in the human body, and thus understand the relationship between microorganisms and human health or diseases.