@eslint/eslintrc is ESLint's configuration system. It's responsible for parsing, validating, merging, and resolving ESLint configuration files (.eslintrc.js, .eslintrc.json, etc.). This package handles the complex logic of determining the final ESLint configuration for a given file, considering cascading configurations, extends properties, overrides, and environment settings. It's a core dependency for ESLint itself and is crucial for defining and enforcing coding standards in JavaScript projects.