Symmetric Encryption, Asymmetric Encryption and Hashing Cryptographic

1. Symmetric encryption. Uses the same public key to encryption and Decryption
Algorithm : DES, AES, 3DES,RC4

2. Asymmetric Encryption: Use public key to encypt the data and private key to decrypt the data.
Like email exchange.
Algorithm : RSA

Sender encypts data with public key and reciever decrypt using private key.

3. Hashing is kind of cryptographic unlike encryption. It is also called one way encryption.
Algorithm : MD5 and SHA-1
It uses secret key or checksum or password salt-random generated value to encrypt the data. It is called one-way hashing as we cannot reverse the original data or decrypt the value back to clear text.

http://packetlife.net/blog/2010/nov/23/symmetric-asymmetric-encryption-hashing/