Tree

• A trees is a acyclic connected graph
• acyclic: no cycles
• connected: all elements are reached from each other (no disjoint segments)
• Parent-Child data structure
• A filesystem directory structure is a tree starting from / (root node)
• Where a folder is the parent and the files are the children

Elements of a tree

• Root: node with no parent (there is only one in the tree)
• Parent: upstream node of a child node
• Child: downstream node of a parent node
• Leaf: nodes with no children
• Sibling: nodes in the same level in the tree