Tree Based Index

What
A tree based index is a one where the search keys are organized into a tree structure

Organization
A tree based index is organized into index nodes and data nodes. The index nodes contain the pair (search key, page id) where page id is the page to find the next node in the sequence.

Searching a Tree Based Index
Searching through a tree based index will take $$log_F B$$ time, where $$F$$ is the fan out of the tree and $$B$$ is the number of leaves of the tree