The Hashtable class represents a collection of key-and-value pairs that are organized based on the hash code of the key. It uses the key to access the elements in the collection.A hash table is used when you need to access elements by using key, and you can identify a useful key value. Each item in the hash table has a key/value pair. The key is used to access the items in the collection.

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If we are having a large no of key value pair at that time we can use HashTable for storing the pairs For more Interview Question You can refer this link csharp interview questions