WhatsApp API glossary: the terms you need, defined plainly
This glossary defines the WhatsApp terms you meet when you build on the API or run campaigns: the 24-hour session window, opt-in, message templates, throughput, webhooks and the difference between the Cloud API and a linked WhatsApp Web session, each with a short example.
Each entry gives a short definition, why the term matters in practice and a link to the guide or feature where it applies. Use it when a term in a guide, a feature page or the API documentation is new to you. Terms without a link are already defined and switch on as their pages go live.
Glossary
Glossary
Click to chat
A link or button that opens a WhatsApp chat with a business.
Conversation pricing
How Meta charges official API messages by conversation category.
Green tick
The verified badge Meta shows next to some business names.
Opt-in
A customer's permission to receive messages from your business.
WABA
WhatsApp Business Account: the Meta account behind official API sending.
BSP
Business Solution Provider: a Meta partner that resells official API access.
Template message
A pre-approved message format required to start official API conversations.
Quality rating
Meta's score for how recipients react to a number's messages.
Messaging tier
The daily limit on how many people an official API number can message.
Session window
The 24 hours after a customer's last message when free-form replies are allowed.
CTWA
Click-to-WhatsApp: ads that open a WhatsApp chat instead of a website.
Coexistence mode
Using the WhatsApp Business app and the Cloud API on the same number.
Conversation category
Meta's pricing categories: marketing, utility, authentication and service.
Cloud API
Meta's official, hosted WhatsApp Business API.
On-premises API
Meta's older self-hosted WhatsApp Business API, now retired.
Webhook
An HTTP callback that sends events to your server as they happen.