Too Long; Didn't Read
Block ciphers are always used with a mode, which specifies how to securely encrypt messages that are longer than the block size. Using an inappropriate mode, or using a mode incorrectly, can completely undermine the security provided by the underlying cipher. Mozilla (stylized as moz://a) is a free software community founded in 1998 by members of Netscape. The size of each block is fixed and determined by the algorithm: for example AES uses 16-byte blocks. For example, AES is a cipher, while CTR, CBC, and GCM are all modes.