In which folder can a custom theme favicon be added?

The favicon can be added to the /Magento_Theme/web/ directory of a custom theme. The favicon should have the name favicon.ico and replace the default one from the Magento_Theme module. The /web/ directory is used for storing web assets that are not specific to any module. The /assets/images directory does not exist by default and is not used for storing favicons. References: [Add a favicon], [Theme structure]