Difference between encrypting something and hashing something What is the difference between encrypting something and hashing something?  in what situations would I want one or the other?
(I am new to cryptography, so hopefully I wouldn't say anything wrong. The following I hope should help give an idea of differences).

In general you always have a plaintext or something that you want to keep secret. This might be a message or a file or a password.

Encrypting: encryption transforms the plaintext into something that cannot be understood - something that doesn't have any meaning. Something unintelligible. You encrypt the message/plaintext by using an algorithm and a key. The output (the ciphertext) always depends on the key. The essential thing about encryption is that you can always recover the plaintext (if you know the key/password), and given a key/password you have only one plaintext. So you can think of encryption/decryption as a way to move back and forward between you plaintext and your cipher text (using a key).
Uses: Encryption is good if you say have a message to send to someone. You encrypt the message with a key and the recipient decrypts with the same (or maybe even a different) key to get back the original message.

Hashing: hashing turns something (usually a key or a password) into a (usually fixed length) string of characters. For example your hashing algorithm might always produce a string that is 8 bytes long. As with encryption you transform something intelligible into something unintelligible. One might call the product of the hashing the hash codes of the hash sums. One difference is that hashing two different messages might produce the same hash values. So you cannot decrypt something that you have hashed. But even though you can't decrypt a hashed value, it is (or it should) in general hard to make two messages that have the same hash value. Another difference is that hashing doesn't require a key.
Uses: One use of hashing is if you want to send someone a file. But you are afraid that someone else might intercept the file and change it. So a way that the recipient can make sure that it is the right file is if you post the hash value publicly. That way the recipient can compute the hash value of the file received and check that it matches the hash value.