Original: In cryptography, Triple DES (3DES) is the common name for the Triple Data Encryption Algorithm (TDEA or Triple DEA) block cipher, which applies the Data Encryption Standard (DES) cipher algorithm three times to each data block.
Simplified: In cryptography, Triple DES is a block cipher derived from the Data Encryption Standard (DES) cipher by using it three times. Triple DES is also known as TDES or, more standard, TDEA (Triple Data Encryption Algorithm).