In the context of DDD, the highlighted core refers to the most critical and complex part of a software system, which embodies the core domain logic and provides the most value to the business. This core should be kept separate from the supporting and generic subdomains and should be developed and maintained by the domain experts and developers who have a deep understanding of the business and its requirements. The highlighted core should be protected and isolated from changes and modifications that do not directly relate to the core domain, which is achieved through the use of bounded contexts, domain events, and other DDD concepts. By keeping the highlighted core separate from the supporting and generic subdomains, the system can maintain a high level of cohesion and modularity, making it easier to understand, maintain, and evolve over time.