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• Authentication allows customers to be sure that the merchant they are sending their credit card details to is who they say they are. It can also allow merchant's to verify that the customer is the real owner of the credit card being used.
• Integrity ensures that the messages have not been tampered with by a third party during transmission.
• Non-repudiation prevents customers or merchants denying they ever received or sent a particular message
• Privacy prevents third parties from reading intercepted messages

• The plaintext is the raw message or data that is to be encrypted.
• A cryptographic algorithm or cipher is a mathematical set of rules that defines how the plain text is to be combined with a key.
• The key is a string of digits.
• The ciphertext is the encrypted message.

If we take the phrase "Web store" and add 2 characters to each letter the phrase becomes "ygd uvqtg". Here:

"Web store" is the plaintext
"add x characters to each letter" is the cryptographic algorithm
"2" is the key
"ygd uvqtg" is the ciphertext

There are two main types of encryption in common use today: secret-key and public-key.