Open addressing is a collision resolution technique used in hash tables, where conflicts are handled by probing for alternative empty slots within the array.

In a hash table, a collision occurs when two or more keys map to the same index. Open addressing addresses these collisions by searching through the array for an available slot to store the value. This probing process continues until an empty slot is found.

There are various probing strategies to resolve collisions. The simplest method is linear probing, where the hash table inspects the next slot in the array sequentially, moving to the next one and so on, until an empty slot is located. However, this approach can lead to a phenomenon known as primary clustering, where long sequences of occupied slots accumulate, thereby increasing the average search time.

To mitigate primary clustering, quadratic probing can be employed. In this method, rather than checking the next adjacent slot, the hash table examines slots that are a certain distance away, with this distance increasing quadratically for each subsequent probe. While this reduces the chances of primary clustering, it can result in another issue called secondary clustering, where specific slots become more frequently probed than others.

Another effective strategy is double hashing, which utilizes a second hash function to determine the probe sequence. This method can help circumvent the clustering problems associated with linear and quadratic probing, but it introduces additional complexity and computational overhead.

In open addressing, the load factor—defined as the ratio of the number of elements to the size of the array—plays a crucial role. As the load factor increases, the probability of collisions and the average search time also rise. Consequently, it is vital to maintain the load factor below a specific threshold and to resize the array when necessary.

In summary, open addressing is an effective technique for managing collisions in hash tables. However, it necessitates careful oversight of the load factor and an appropriate probing strategy to ensure optimal performance.