How secure is AES against brute force attacks?

In the world of embedded and computer security, one of the often debated topics is whether 128-bit symmetric key, used for AES (Advanced Encryption Standard) is computationally secure against brute-force attack. Governments and businesses place a great deal of faith in the belief that AES is so secure that its security key can never be broken, despite some of the inherent flaws in AES. This article describes the strength of the cryptographic system against brute force attacks with different key sizes and the time it takes to successfully mount a brute force attack factoring future advancements in processing speeds.