A hashcode is usually used as an efficient way of searching for stored objects.
Say you have a list of 1000 names, it would take a reasonable amount of time to search for the name "Jeremy Thornton" in the list.
If however you stored the names according to their hashed value (which is what the HashX type containers do) you just search for the hash of "Jeremy Thornton" - an integer - instead.
As integer processing is much faster than
string processing the search is much quicker.
Hoper this helps,
Jeremy.