Symmetric-key cryptography is a term used for cryptographic algorithms that use the same key for encryption and for decryption. 

- In encryption, the algorithm transforms the data in a format which cannot be understood by anyone. 

- A special & confidential key is required to decipher that data set into a readable format. 

- As the intended recipient receives the ciphered data, the confidential key transforms it back to the readable format.

Three main steps involved in symmetric encryption are:

- The sender uses an alpha-numeric string, termed as the encryption key, to cipher confidential data.

- The ciphered message, termed as ‘ciphertext’ looks like random numbers whose real meaning can’t be understood.

- The intended recipient has the same deciphering key that transforms the ciphertext into the previous format.

- The secret keys used by the senders and the recipients might be a specially developed passcode or a special sequence developed by the random number generator which also decrypts them back.

A. Block Encryption: In this, the set numbers of bits are ciphered in electronic data blocks with the help of a secret key. As the information is ciphered, the system stores data in the internal memory.

B. Stream Encryption: In this tactic, the data encryption directly streams in place of being stored in the system’s internal memory.

Key Features of Symmetric key Cryptography 

1. Single Key Usage

The same key is used for both encryption and decryption.

2. Speed

Symmetric encryption algorithms are generally faster than asymmetric ones, making them suitable for encrypting large amounts of data.

3. Key Management

Securely sharing and managing the secret key between parties can be challenging, especially in large systems.

4. Common Algorithms

Some widely used symmetric encryption algorithms include:

- AES (Advanced Encryption Standard)

- DES (Data Encryption Standard)

- 3DES (Triple DES)

- Blowfish

- RC4

1. Data encrypting/decrypting

- SKC widely applies to protect sensitive data either statically stored in some device or transmitted through the network. 

- Some of these applications include the authentication of users' credentials, encryption of email messages, and financial transactions.

2. Secure communication

- The majority of the communication protocols commonly used are SSL/TLS, which use the combination of symmetric and asymmetric key encryption to ensure the confidentiality and integrity of exchanged information between two parties.

3. Authenticity verification

- In some places, SKC is applied using techniques like message authentication codes (MACs) and keyed-hash MACs (HMACs) to authenticate the messages by verifying their authenticity and integrity, thus ensuring tamper-resistant communication.

4. File and disk encryption

- Full-disk encryption software and file encryption tools also apply SKC to encrypt sensitive data stored in hard disks or portable storage devices.

5. Virtual private networks

- VPN technologies are technologies that aim to provide confidential communication channels free from eavesdropping.

-  Some of these may use symmetric or asymmetric key encryption to connect remote users and corporate networks.