BST can refer to two different things:

1. British Summer Time: During British Summer Time, civil time in the United Kingdom is advanced one hour forward of Greenwich Mean Time, in effect changing the time zone from UTC±00:00 to UTC+01:00, so that mornings have one hour less daylight, and evenings one hour more. BST begins at 01:00 GMT every year on the last Sunday of March and ends at 01:00 GMT (02:00 BST) on the last Sunday of October.

2. Binary Search Tree: In computer science, a binary search tree (BST) is a rooted binary tree data structure with the key of each node in the left subtree being less than or equal to the nodes key, and the key of each node in the right subtree being greater than or equal to the nodes key. Binary search trees allow for fast lookup, addition, and removal of data items, with lookup performance proportional to that of binary logarithm. BSTs were devised in the 1960s for the problem of efficient storage of labeled data and are attributed to Conway Berners-Lee and David Wheeler.