A high-level data structure, made of nodes, each with a maximum of 2 children (left and right). Nodes with no children are called leaves, and two nodes with the same parent are known as siblings.
Binary trees are a particular type of tree, where each node has a maximum of two children. Binary trees are often used in efficient searching and sorting algorithms, as well as common systems such as Huffman coding.
Challenges under this tag often involve answers taking trees as input in a serialised/traversed format. Note that trees can be traversed in at least 5 different ways: pre-order depth first, in-order depth first, reverse in-order depth first, post-order depth first and breadth first. To read more about these, see here
This often overlaps with the tree-traversal tag.
