AES takes a plaintext block 16 bytes (128 bits) and key length 16, 24, 32 bytes (128, 192, 256 bits) AES-128, AES-192, AES-256 depending on key length.
The input to encryption or decryption algorithm in AES is 128 bits block = 16 bytes as 4x4 matrix, this matrix is copied into a state array, then the state array passes through and modified in each stage and then the state array is copied to output matrix.
