Cryptographic Hash
A cryptographic hash is an algorithm which maps a string to a fixed sized string, with a method that is difficult or impossible to revert.
Some famous algorithms: MD5, SHA1, SHA256, HAVAL, Bcrypt.
Other algorithms include crc32(), though it is not considered a cryptography.
While the extension hash only process hashes, there are other extensions which offer these features: openssl, sodium and password hashing. Mhash and mcrypt are older PHP extensions, which are now discontinued.
<?php
echo hash('ripemd160', 'The quick brown fox jumped over the lazy dog.');
// produces ec457d0a974c48d5685a7efa03d137dc8bbde7e3
?>