There are of course a wide range of cryptographic algorithms in use. The following are amongst the most well known:
This is the 'Data Encryption Standard'. This is a cipher that operates on 64-bit blocks of data, using a 56-bit key. It is a 'private key' system. Further Details on the DES Algorithm
RSA is a public-key system designed by Rivest, Shamir, and Adleman. Further Details on the RSA Algorithm
A 'hash algorithm' is used for computing a condensed representation of a fixed length message/file. This is sometimes known as a 'message digest', or a 'fingerprint'..
MD5 is a 128 bit message digest function. It was developed by Ron Rivest. Further Details on the MD5 Algorithm
This is the Advanced Encryption Standard (using the Rijndael block cipher) approved by NIST.
SHA-1 is a hashing algorithm similar in structure to MD5, but producing a digest of 160 bits (20 bytes).Because of the large digest size, it is less likely that two different messages will have the same SHA-1 message digest. For this reason SHA-1 is recommended in preference to MD5.
HMAC is a hashing method that uses a key in conjunction with an algorithm such as MD5 or SHA-1. Thus one can refer to HMAC-MD5 and HMAC-SHA1.