The CMS Collaboration has developed the COMBINE software package for statistical analyses. Originally designed for Higgs boson searches, COMBINE is now used in most CMS measurements and searches. It is not CMS-specific and serves as a reference for external users. The software uses a datacard configuration file for statistical models and allows users to run examples via a Docker container. The package is continuously updated to handle increasing data sets and analysis complexity. The paper provides an overview of COMBINE's statistical methods and capabilities, with detailed instructions on installation, statistical models, analysis types, and usage. The software uses ROOT, ROOFIT, and ROOSTATS. It supports counting and shape analyses, with datacards defining observables, processes, and systematic uncertainties. COMBINE includes routines for statistical diagnostics and is used in various CMS publications, including Higgs boson measurements, supersymmetry searches, and top quark mass measurements. The paper describes the statistical model, which factors observables and parameters, and provides examples of datacards for counting and shape analyses. The software is used for likelihood calculations, confidence intervals, and goodness-of-fit tests. The paper also details the installation process, dependencies, and usage of COMBINE for statistical analyses.The CMS Collaboration has developed the COMBINE software package for statistical analyses. Originally designed for Higgs boson searches, COMBINE is now used in most CMS measurements and searches. It is not CMS-specific and serves as a reference for external users. The software uses a datacard configuration file for statistical models and allows users to run examples via a Docker container. The package is continuously updated to handle increasing data sets and analysis complexity. The paper provides an overview of COMBINE's statistical methods and capabilities, with detailed instructions on installation, statistical models, analysis types, and usage. The software uses ROOT, ROOFIT, and ROOSTATS. It supports counting and shape analyses, with datacards defining observables, processes, and systematic uncertainties. COMBINE includes routines for statistical diagnostics and is used in various CMS publications, including Higgs boson measurements, supersymmetry searches, and top quark mass measurements. The paper describes the statistical model, which factors observables and parameters, and provides examples of datacards for counting and shape analyses. The software is used for likelihood calculations, confidence intervals, and goodness-of-fit tests. The paper also details the installation process, dependencies, and usage of COMBINE for statistical analyses.