These are some of the notes that I review and refer to when working with students preparing for the CompTIA Security+ exam.

Cryptography is the practice of protecting information using specialized algorithms, hashes, and signatures.

Encoding transforms data or information into a specific format for storage, transmission, or processing.

Decoding is converting encoded data back into its original, readable format.

Encoding and decoding are terms used to describe the use of cryptographic processes.
Encoding and decoding are computing processes that transform data from one format to another for purposes such as storage, transmission, and communication. It is important to recognize that these processes are not limited to cryptography; they are also used in various non-cryptographic functions. For instance, encoding can involve converting text into a specific character encoding like ASCII or Unicode, while decoding can transform binary data into a readable format such as Base64.

Plaintext refers to readable data in its original, unencrypted form that can be easily understood without any special decryption or conversion process.

A cryptographic key is a data string used with a cryptographic algorithm to secure information. Encryption encodes plaintext using a cipher and a key into ciphertext so authorized parties can only read it using the same cipher and the correct key.

Ciphertext is the output of the encryption process, a scrambled, unreadable version of the original plaintext message.

A cipher is a method used in cryptography to encrypt or decrypt data, decodes it from plaintext) into ciphertext.

Decryption is converting ciphertext back into its original, readable form.

Cryptanalysis is the art or process of deciphering encoded messages without being told the key.