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 O(1) time complexity for insertion, deletion, and lookup operations by storing key-value pairs in a way that minimizes collisions. This makes it fundamental for tasks requiring fast data retrieval, such as caching, database indexing, and implementing sets or dictionaries.
Developers should learn hash tables when building applications that require high-performance data access, such as real-time systems, search engines, or any scenario where quick lookups are critical. They are essential for implementing caches (e.g., in web servers), handling unique data in sets, and optimizing algorithms in competitive programming or large-scale data processing. Understanding hash tables helps in designing efficient systems and is a key concept in computer science interviews and practical software development.