Encryption converts plain text into ciphertext using an algorithm. There are two main types: asymmetric which is more secure but slower, and symmetric which is faster but less secure. Encryption is widely used to protect passwords, private data, and ensure document integrity. It is important for encryption systems to have strong key management. Common uses of encryption include web browsing, email, hard drives, and operating systems. Electronic payments can be made using credit cards, e-checks, or e-cash and involve various issues regarding security, costs, and privacy. Authentication is used to verify trusted sources and can involve passwords, biometrics, or digital signatures. Businesses can accept electronic payments by using a payment service or handling transactions in-house.