Hashing and message digests

Please provide a detailed response to the below to include specific details and examples.

Hashing  should not be confused with the previous forms of encryption that we  have discussed. Although they share similarities, there are many  differences. Please discuss both the similarities and differences  between the previous encryption methods we have discussed and hashing.  In addition, what is a message digest and what would we use it for? 

Peer Response(s):  Read  the responses from your peers and offer a constructive critique or  additional information that adds substantively to the discussions.   Remember, a response that simply states that their post was good or that  you liked it is not considered substantive.  You should contribute to  the learning via your posts and responses.  Be sure to acknowledge any  outside sources you use.