This review discusses the recent emergence of a novel coronavirus (2019-nCoV), which has caused an outbreak of unusual viral pneumonia in Wuhan, China. Coronaviruses (CoVs) are important pathogens that can infect a wide range of hosts, including humans, livestock, birds, and bats. The 2019-nCoV, identified as a betacoronavirus, is closely related to bat SARS-like coronaviruses and is more distantly related to SARS-CoV. The genome of CoVs is a single-stranded positive-sense RNA (~30 kb) with 5'-cap structure and 3'-poly-A tail. The genome is used as a template to translate polyproteins, which are processed into non-structural proteins (nsps) that form the replication-transcription complex (RTC). Subgenomic RNAs (sgRNAs) are synthesized by the RTC and serve as templates for subgenomic mRNAs. The genome of a typical CoV contains at least six open reading frames (ORFs), with ORF1a/b encoding 16 nsps. Other ORFs encode structural proteins such as spike (S), membrane (M), envelope (E), and nucleocapsid (N) proteins. The nsps are more conserved, while the structural proteins are more diverse and require adaptation to new hosts. The 2019-nCoV has a genome structure typical of betacoronaviruses and is more closely related to bat SARS-like coronaviruses. The pathogenesis of CoVs varies, with some causing mild upper respiratory disease and others causing severe lower respiratory tract infections. The 2019-nCoV can infect the lower respiratory tract and cause pneumonia in humans, but the symptoms are milder than SARS and MERS. The virus is believed to have originated from the Wuhan seafood market, and transmission from fish to humans is unlikely. The virus is likely spread through human-to-human transmission. The review also discusses the functions of non-structural and structural proteins in CoV replication and the current lack of effective treatments or vaccines for CoVs. The best measures for controlling CoV outbreaks include controlling the source of infection, early diagnosis, isolation, and timely publication of epidemic information. Personal hygiene, mask-wearing, and avoiding crowded places are recommended to prevent CoV infection. The review highlights the need for further research into CoV biology, pathogenesis, and the development of effective therapies and vaccines.This review discusses the recent emergence of a novel coronavirus (2019-nCoV), which has caused an outbreak of unusual viral pneumonia in Wuhan, China. Coronaviruses (CoVs) are important pathogens that can infect a wide range of hosts, including humans, livestock, birds, and bats. The 2019-nCoV, identified as a betacoronavirus, is closely related to bat SARS-like coronaviruses and is more distantly related to SARS-CoV. The genome of CoVs is a single-stranded positive-sense RNA (~30 kb) with 5'-cap structure and 3'-poly-A tail. The genome is used as a template to translate polyproteins, which are processed into non-structural proteins (nsps) that form the replication-transcription complex (RTC). Subgenomic RNAs (sgRNAs) are synthesized by the RTC and serve as templates for subgenomic mRNAs. The genome of a typical CoV contains at least six open reading frames (ORFs), with ORF1a/b encoding 16 nsps. Other ORFs encode structural proteins such as spike (S), membrane (M), envelope (E), and nucleocapsid (N) proteins. The nsps are more conserved, while the structural proteins are more diverse and require adaptation to new hosts. The 2019-nCoV has a genome structure typical of betacoronaviruses and is more closely related to bat SARS-like coronaviruses. The pathogenesis of CoVs varies, with some causing mild upper respiratory disease and others causing severe lower respiratory tract infections. The 2019-nCoV can infect the lower respiratory tract and cause pneumonia in humans, but the symptoms are milder than SARS and MERS. The virus is believed to have originated from the Wuhan seafood market, and transmission from fish to humans is unlikely. The virus is likely spread through human-to-human transmission. The review also discusses the functions of non-structural and structural proteins in CoV replication and the current lack of effective treatments or vaccines for CoVs. The best measures for controlling CoV outbreaks include controlling the source of infection, early diagnosis, isolation, and timely publication of epidemic information. Personal hygiene, mask-wearing, and avoiding crowded places are recommended to prevent CoV infection. The review highlights the need for further research into CoV biology, pathogenesis, and the development of effective therapies and vaccines.