What is Encryption and Decryption ? How does it work ?

Encryption

Encryption is a process which transform the original information into an unrecogniseble form. This new form of the message is entirely different from the original message. That's why a hacker is not able to read the data as senders use an encryption algorithem.Encryption is usually done key algorithm.
Data is encrypted to make it safe from stealing. however many known companies also encrypt their data to keep their trade secret from their competitors.

Decryption

Decryption is a process of converting encoded/encrypted data in a form that is readable and understandable by a human and a computer. This method is performed by un-encrypting the text manually or by using keys to decrypt the original data.
Authentication
Authentication is the process of verifying who you are. When you login to a pc with a username and password you are authenticating. Authenticating is about validating your credentials like username, user id and password to verify your identity. The system determine whether you are the same person who login before. In public and private network the system authentication , The user identity via login password. Authentication is usually done by a username and password and sometimes in connection factors of authentication which refers to the various ways to be authentication.
Transmission Media
Transmission media is a physical path that carries data between a sender and receiver. It's also known as Communication channel.
Transmission Media is divided in Two types of media and have its sub types /-

• 1) Guided Media
  1. Twisted Pair Cable
  2. Optical Fiber Cable
  3. Coaxial Cable
• 2) Unguided Media
  1. Radio Wave
  2. Infrared
  3. Micro wave