A trie, also known as a prefix tree, is a specialized tree structure used to store strings in a way that facilitates fast retrieval, particularly useful for prefix-based searches. Each node in a trie represents a single character, and strings are stored as paths through the tree, with common prefixes being shared among strings. This structure allows efficient lookups, insertions, and deletions of words, making it ideal for applications like autocomplete systems, spell checkers, and IP routing. In TypeScript, you can implement a trie by defining a class for the nodes, where each node has a map (or object) that stores its children and a boolean flag indicating whether a word ends at that node. To insert a word, you traverse the trie, adding new nodes as necessary. To search for a word or prefix, you traverse the nodes following the characters of the query. Tries are particularly useful in scenarios involving large datasets of strings, as they can dramatically reduce the search time compared to other data structures like arrays or hashmaps. By implementing a trie in TypeScript, you can build efficient solutions for string search problems in a variety of real-world applications.