When a customer messages you, a 24-hour window opens. Inside it you can reply with any text, image, PDF or buttons. After it closes you can only send an approved template.
Why it matters
Templates are billed per message and need Meta approval. Free-form replies inside the window are the cheapest and most flexible way to talk to customers, so the goal is to start conversations that customers answer.
Practical tips
Ask a question in your template so a reply reopens the window. Use quick-reply buttons for one-tap answers. In baseNode the inbox shows the time left on each window, and a customer reply restarts it.
Click-to-WhatsApp ads and some entry points can give a longer free window. Check Meta's current terms for the details that apply to you.