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 minimizing collisions through techniques like chaining or open addressing. Hash tables are fundamental in computer science for fast data retrieval and are widely used in applications requiring quick access to stored information.
Developers should learn hash tables when building systems that require fast key-value pair lookups, such as caching mechanisms, database indexing, or implementing dictionaries and sets in programming languages. They are essential for optimizing performance in scenarios like counting frequencies, detecting duplicates, or storing configuration data where constant-time access is critical, making them a core concept for algorithm design and software efficiency.