What it means
Authentication templates are reserved for security-related messages: OTPs, two-factor codes, account verification. They have a stricter format than marketing or utility templates: usually a short codenumber, a brief explanation, and nothing else. No links, no marketing copy, no upsells.
Meta charges a per-message rate that is typically the lowest of the three categories, reflecting their narrow scope. Like the others, the rate varies by country.
Why it matters
If your product or app uses WhatsApp for OTP delivery (instead of SMS), authentication templates are mandatory. They are also a lot cheaper than running international SMS through traditional carriers, which is one reason WhatsApp authentication is gaining ground in fintech, gaming, and gig-economy apps.
Misusing authentication templates (sending marketing copy in them) is one of the fastest ways to get an account flagged.
Example
A digital banking app moves OTP delivery from SMS to WhatsApp authentication templates. Their per-OTP cost in Southeast Asia drops by roughly 70 percent, and delivery rates improve because most users keep WhatsApp open while they have lost track of their SMS inbox.