Hash tables, also known as hash maps, are data structures that store key-value pairs and provide fast lookups, insertions, and deletions in constant average time, O(1). The key idea behind hash tables is the use of a hash function, which converts a key into an index in an array where the corresponding value is stored. In TypeScript, you can implement hash tables using objects or the built-in `Map` class. When using an object, the keys are converted to strings, while `Map` allows for more flexible key types like numbers, objects, or even functions. To implement a basic hash table, you define a hash function that maps keys to unique indexes in an array. In cases where multiple keys hash to the same index (a collision), techniques like chaining (using linked lists) or open addressing (probing) are used to resolve conflicts. Hash tables are widely used in various applications, such as implementing dictionaries, caches, and sets. Their fast access time makes them ideal for situations where you need to frequently add, remove, or look up data based on a key, such as in real-time systems, databases, or compilers.