What is 3DES?

Triple DES (3DES) is a symmetric-key block cipher algorithm, which applies the DES cipher algorithm three times to each data block. It's used to enhance the security of DES, which was vulnerable to brute-force attacks. While 3DES is more secure than DES, it is considerably slower than newer algorithms like AES and is considered a legacy encryption algorithm. 3DES is commonly used in financial transactions, VPNs, and other security protocols where strong encryption is required but newer algorithms aren't feasible.