B-tree

In computer science, b-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing for nodes with more than two children. Unlike other self-balancing binary search trees, the B-tree is well suited for storage systems that read and write relatively large blocks of data, such as databases and file systems.
— Wikipedia

            hello
      ┌───────┴───────┐
      1               1
  ┌───┴───┐       ┌───┴───┐
  2       3       2       3
┌─┴─┐   ┌─┴─┐   ┌─┴─┐   ┌─┴─┐
4   5       6   4   5       6

Algorithm	Average	Worst case
Space	O(n)	O(n)
Search	O(log n)	O(log n)
Insert	O(log n)	O(log n)
Delete	O(log n)	O(log n)