The full form of OTP is One Time Password. OTP is a unique and temporary code that is used to authenticate users during specific transactions. It is a type of security password that is valid only for a single-use or transaction and on a single computer, mobile device, etc., which is used for the transaction. OTP provides an extra layer of security while using your debit cards, credit cards for online transactions such as mobile recharge, online shopping, paying bills, etc. . It is typically a 4 to 6 digit code that is sent to the users registered mobile number or email address. OTPs may replace authentication login information or may be used in addition to it to add another layer of security. OTPs are more secure than static passwords, especially user-created passwords, which can be weak and/or reused across multiple accounts. The OTP system employs algorithms that generate random valid codes for a limited period of time. There are three primary methods of generating OTPs: Time-based OTP (TOTP), HMAC-based OTP (HOTP), and SMS-based OTP.