The Decision Editor is the primary means to define a set of business rules in the form of DMN Decision Tables. This form of rules looks like a spreadsheet, making it easy for business users to understand and describe their business rules. Decision Tables can be used standalone, although they are usually referenced and used within process or case models.
DMN (Decision Model and Notation) is a published standard to describe decisions and business rules. The DMN standard is complementary to the BPMN and CMMN standards and extends them by integrating specific DMN decision tasks into the process and case model.
With DMN you are able to:
Document and comply with business rules for regulatory compliance and security audits.
Automate manual decision making.
Improve and simplify BPMN processes where decisions were modeled using BPMN expressions.
You can more detailed information in the DMN standard.