The article introduces IMG ER, an Expert Review version of the Integrated Microbial Genomes (IMG) system, designed to systematically and efficiently revise microbial genome annotations. IMG ER supports the review and curation of annotations for both new and publicly available microbial genomes within IMG's integrated genome framework. New genome datasets are included into IMG ER before their public release, either with their original annotations or with annotations generated by IMG ER's annotation pipeline. IMG ER tools address annotation problems detected through IMG's comparative analysis tools, such as missing genes or genes without associated functions. Over the past year, IMG ER has been used to improve the annotations of about 150 microbial genomes. The system provides tools for filling annotation gaps, enhancing metadata, and characterizing microbial genomes. IMG ER is available at http://img.jgi.doe.gov/er and requires an account for access. The article also discusses the methods used for microbial genome annotation, including the use of automated methods for gene prediction and functional annotation. It highlights the effectiveness of IMG analysis tools in revealing gaps in annotations and the curation tools provided by IMG ER for addressing these gaps. The results section details the application of IMG ER in various studies, including the revision of annotations for 380 genomes and the publication of several research papers. The discussion section emphasizes the efficiency and capabilities of IMG ER, particularly in the context of metagenome datasets, and outlines future extensions and improvements.The article introduces IMG ER, an Expert Review version of the Integrated Microbial Genomes (IMG) system, designed to systematically and efficiently revise microbial genome annotations. IMG ER supports the review and curation of annotations for both new and publicly available microbial genomes within IMG's integrated genome framework. New genome datasets are included into IMG ER before their public release, either with their original annotations or with annotations generated by IMG ER's annotation pipeline. IMG ER tools address annotation problems detected through IMG's comparative analysis tools, such as missing genes or genes without associated functions. Over the past year, IMG ER has been used to improve the annotations of about 150 microbial genomes. The system provides tools for filling annotation gaps, enhancing metadata, and characterizing microbial genomes. IMG ER is available at http://img.jgi.doe.gov/er and requires an account for access. The article also discusses the methods used for microbial genome annotation, including the use of automated methods for gene prediction and functional annotation. It highlights the effectiveness of IMG analysis tools in revealing gaps in annotations and the curation tools provided by IMG ER for addressing these gaps. The results section details the application of IMG ER in various studies, including the revision of annotations for 380 genomes and the publication of several research papers. The discussion section emphasizes the efficiency and capabilities of IMG ER, particularly in the context of metagenome datasets, and outlines future extensions and improvements.