The Importance of a One Time Password for Online Security
Discover how one-time passwords (OTPs) strengthen account security and where they fit in your overall authentication strategy.
What Is a One-Time Password?
A one-time password (OTP) is a code that can be used only once and usually expires after a short period. OTPs are commonly sent via SMS, email, or generated in an authenticator app. Because they change constantly, they provide an extra layer of security beyond a static password.
OTPs are a key building block of multi-factor authentication. Even if an attacker steals your regular password, they typically cannot log in without the current OTP as well, which significantly reduces the risk of unauthorized access.
Benefits and Limitations of OTPs
The main benefit of OTPs is that they prevent attackers from reusing credentials captured through phishing, keyloggers, or data breaches. Once a code has been used—or has expired—it is useless to anyone who tries to replay it later. OTPs also allow services to step up security selectively for sensitive actions such as changing account settings or making large payments.
However, not all OTP delivery methods are equally secure. SMS codes can be intercepted through SIM-swapping attacks or insecure phone networks. Authenticator apps and hardware security keys generally offer stronger protection because they rely on cryptographic secrets stored on your device, not on your phone number.
How to Use One-Time Passwords Safely
Whenever possible, enable OTP-based multi-factor authentication on your most important accounts, such as email, banking, and cloud storage. Prefer authenticator apps or hardware keys over SMS where those options are available. Store recovery codes in a safe place in case you lose access to your device.
Be cautious about sharing codes: no legitimate service will ask you to read an OTP aloud or send it back to them after they just sent it. Treat any such request as a red flag for social engineering. If you receive unexpected OTP messages, it may indicate that someone is trying to log in as you, so review your account security settings promptly.