When to use a HashTable

Question

In C#, I find myself using a List, IList or IEnumerable 99% of the time. Is there a case when it would be b

Answer 1

Hash-tables are good choices if you are often doing "for something in collection" and you aren't concerned about the order of items in the collection.

Hash-tables are indexes. You can maintain a hash-table to index a list, so you can both choice to access it in order or randomly based upon the key.