A hierarchical data structure consisting of nodes connected by edges, with one root node at the top and branches extending downward to child nodes. Each node can have multiple children but only one parent (except the root, which has no parent).
The metaphor comes from botanical trees, used in computing since the 1950s because the branching structure resembles an upside-down tree. The terminology (root, branches, leaves, parent, child) all derive from this natural analogy.
A tree structure is like a family tree or corporate organization chart - there's one person at the top (CEO/root), they have direct reports (children), who have their own direct reports, and so on. Just like in a company, information flows up and down through the hierarchy, and everyone has exactly one boss (except the CEO)!
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