GitHub Advanced Security's secret scanning feature is designed to prevent credential leaks by detecting over 180 types of secrets and allowing organizations to define custom patterns for unique secret types. Since June 2021, support for custom patterns has been enhanced to include dry runs, enabling users to experiment with pattern filtering and iteratively improve detection accuracy without committing changes. The feature supports up to 500 custom patterns per organization and 100 per repository, and it includes the ability to edit existing patterns and track updates in audit logs. Custom patterns have become increasingly popular, with a nearly 50% increase in usage since the introduction of dry runs in public preview. Once satisfied with a custom pattern, users can publish it to generate official alerts, while GitHub Advanced Security continues to offer capabilities like code scanning, supply chain security, and Dependabot alerts to secure organizations globally.