ARIA is a block cipher developed in South Korea, and an official standard (KS X 1213) there. It uses 128-bit blocks and supports keys of 128, 192 or 256 bits; these numbers are identical to those for AES, so ARIA can be used as a drop-in replacement for AES in all applications.
The structure of ARIA is a substitution-permutation network. The permutation multiplies a 128-bit vector by a 16x16 Boolean matrix to get another 128-bit vector.
There is a home page for the cipher. Internet RFC 5794 gives a specification of the algorithm for Internet use and RFC 6209 discusses its applications.