Hash Table
A hash table is a data structure that implements an associative array abstract data type, mapping keys to values using a hash function to compute an index into an array of buckets or slots. It provides efficient average-case time complexity of O(1) for insertion, deletion, and lookup operations by reducing the search space through hashing. This makes it ideal for scenarios requiring fast data retrieval, such as caching, database indexing, and implementing sets or dictionaries.
Developers should learn and use hash tables when they need high-performance key-value storage with constant-time average operations, particularly in applications like caching (e.g., Redis), symbol tables in compilers, or handling unique elements in sets. It's essential for optimizing algorithms in competitive programming, web development for session management, and systems programming where quick data access is critical, such as in-memory databases or network routing tables.