A hash function is any well-defined procedure or mathematical function that converts a large amount of data into a small datum, usually a single integer. For questions about the Twitter and Facebook # symbol, use hashtag
PBKDF2 (Password-Based Key Derivation Function 2) is a key derivation function that is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series.
"Key derivation algorithms such as bcrypt and pbkdf2 aka rfc2898derivebytes are much slower than standard hash algorithms"
from question "Rfc2898DeriveBytes vs Sha2 hash generation for passwords"
"A key-stretching algorithm like pbkdf2 applies a quicker hash like sha512 thousands of times typically causing the hash generation to take 1 5 of a second or so"
from question "What algorithm should I use to hash passwords into my database?"
"Pbkdf2 is more secure than a simple hash or even a salt hash"
from question "TripleDES TransformFinalBlock occasionally giving 'Bad Data. ' error"
"Key strengthening techniques such as bcrypt or pbkdf2 are generally considered better than plain hash since cracking them requires more resources"
from question "Password Hashing"