Triple DES (3DES) is a symmetric-key block cipher that applies the Data Encryption Standard (DES) algorithm three times to each data block. This method enhances security by increasing the key length, making it more resistant to brute-force attacks compared to single DES. In 3DES, data is encrypted with one key, decrypted with a second key, and then encrypted again with a third key. This process effectively strengthens the encryption, but it also makes the algorithm slower than its predecessor. Despite its improvements, 3DES is gradually being phased out in favor of more secure algorithms like AES (Advanced Encryption Standard).