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What are the main components of a UML class diagram?

A UML class diagram has three main components: (1) Classes — boxes divided into three sections: class name (top), attributes (middle), and methods (bottom); (2) Relationships — inheritance (solid line + hollow arrow), composition (filled diamond), aggregation (open diamond), association (solid line), dependency (dashed arrow), and realization (dashed + hollow arrow); (3) Multiplicity — numbers on relationship ends showing cardinality (1, 0..*, 1..n). Use this tool to draw and export class diagrams as SVG or PNG.