A hash table is a data structure that can map keys to values.
It uses a hash function to compute an index where the desired value
can be found.
A hash table offers very fast insertions and searching methods.
The performance of hash tables is often close to O(1) in most of its
operations, but it depends on a number of factors such as the overall
This performance comes from the fact that hash tables are based on
the array data structure.
When the array index of an object is known, the position is nothing more than a
table lookup using the array index.