In the early 2000s, software development was plagued by a silent killer: . Not technical complexity (servers, networks, languages), but domain complexity —the difficulty of translating real-world business rules into code. Evans observed a chronic disconnect: business experts spoke in logistics, finance, or medicine, while developers spoke in tables, objects, and SQL queries.
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| Pattern | Page Range (approx) | What It Solves | | :--- | :--- | :--- | | | 61-70 | An object defined by its identity (e.g., a Person, an Order) | | Value Object | 71-80 | An object defined only by its attributes (e.g., Color, Money, Address) | | Aggregate | 126-140 | A cluster of objects treated as a single unit (e.g., an Order with LineItems) | | Domain Event | 200+ (introduced later) | Something meaningful that happened in the domain | | Repository | 150-160 | A mechanism to retrieve Entities without exposing database details | In the early 2000s, software development was plagued