This review provides an overview of the general features of coronaviruses (CoVs) and describes the diseases they cause in humans and animals. The recent emergence of a novel coronavirus (2019-nCoV) causing an outbreak of unusual viral pneumonia in Wuhan, China, highlights the ongoing risk posed by CoVs to public health. CoVs are important pathogens that can infect various respiratory, gastrointestinal, hepatic, and central nervous systems in humans and many wild animals. The outbreaks of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) have demonstrated the potential for animal-to-human and human-to-human transmission of new CoVs. The genome of CoVs is a single-stranded positive-sense RNA (~30 kb) with 5′-cap structure and 3′-poly-A tail. The genomic RNA is used to translate polyprotein 1a/1ab, which encodes non-structural proteins (nsps) and four main structural proteins: spike (S), membrane (M), envelope (E), and nucleocapsid (N). The functions of these proteins and nsps are crucial for viral replication and pathogenesis. The review also discusses the diversity of CoV pathogenesis, including the different host ranges and tissue tropisms of various CoVs. The current lack of specific antiviral therapies and vaccines for CoVs emphasizes the need for effective treatments and preventive measures, such as early diagnosis, isolation, and public health interventions.This review provides an overview of the general features of coronaviruses (CoVs) and describes the diseases they cause in humans and animals. The recent emergence of a novel coronavirus (2019-nCoV) causing an outbreak of unusual viral pneumonia in Wuhan, China, highlights the ongoing risk posed by CoVs to public health. CoVs are important pathogens that can infect various respiratory, gastrointestinal, hepatic, and central nervous systems in humans and many wild animals. The outbreaks of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) have demonstrated the potential for animal-to-human and human-to-human transmission of new CoVs. The genome of CoVs is a single-stranded positive-sense RNA (~30 kb) with 5′-cap structure and 3′-poly-A tail. The genomic RNA is used to translate polyprotein 1a/1ab, which encodes non-structural proteins (nsps) and four main structural proteins: spike (S), membrane (M), envelope (E), and nucleocapsid (N). The functions of these proteins and nsps are crucial for viral replication and pathogenesis. The review also discusses the diversity of CoV pathogenesis, including the different host ranges and tissue tropisms of various CoVs. The current lack of specific antiviral therapies and vaccines for CoVs emphasizes the need for effective treatments and preventive measures, such as early diagnosis, isolation, and public health interventions.