Hashing is a process of converting any given key or a string of characters into another value using a hash function. The result of a hash function is known as a hash value or simply, a hash. Hashing is a technique or process of mapping keys and values into a hash table by using a hash function. The values returned by a hash function are called hash values. Hashing is a computationally and storage space-efficient form of data access that avoids the non-constant access time of ordered and unordered lists and structured trees, and the often exponential storage requirements of direct access of state spaces of large or variable-length keys.
Hashing is relevant to data indexing and retrieval, digital signatures, cybersecurity, and cryptography. Hashing is most commonly used to implement hash tables, which store data in the form of key and value pairs. The key helps identify the data and operates as an input to the hashing function, which generates new values according to a mathematical hashing algorithm. Hashing uses functions or algorithms to map object data to a representative integer value. A hash can then be used to narrow down searches when locating these items on that object data map.
A good hash function uses a one-way hashing algorithm, meaning that the hash cannot be converted back into the original key. However, two keys can generate the same hash, which is known as a collision. There are several ways to handle collisions, such as separate chaining, open addressing, and double hashing.
Hashing has several advantages in data structures, including key-value support, fast data retrieval, efficiency, memory usage reduction, scalability, and security. Hashing is also used in data authentication and security to ensure that the data received wasn’t somehow changed along the way.
