Tree

Definitions

A hierarchical data structure composed of nodes connected by edges, where each node has zero or more children and exactly one parent (except the root, which has none). Common variants include binary trees, B-trees, tries, and ASTs, and the structure underlies everything from file systems to DOM rendering to database indexes.
In plain English: A way of organizing data in a branching hierarchy, like a family tree where each item can have children beneath it.
Example: "The compiler parses your source code into an abstract syntax tree before it can do any optimization passes."