Answer:
Trees are used to store collections of data, usually key/value pairs. Trees generally have quite low (logarithmic) time complexity for many common operations which makes them desirable data-structures in many situations. There are many types of trees some of which are 'self-balancing'. The analysis
The following is a list of operations with their big-O time complexity assuming n nodes already in tree
find min - O(log(n))
find max - O(log(n))
insert 1 node - O(log(n))
in-order,reverse order, post order or pre-order traversal - O(n)
delete node O(log(n))
this is a little simplistic and varies between types of tree but any application (such as databases) where you need lookup,insertion and deletion to all be fast trees can be very valuable.