Official Business Account (verified badge)
Updated
Quick answer: An Official Business Account (OBA) is a WhatsApp Business API phone number that Meta has given a verified badge — formerly a green tick, now a blue check — next to the business name. To get it you need the API, a completed Meta Business Verification, two-step verification and proof that your brand is notable, such as independent press coverage.
A WhatsApp Business API number with Meta's verified badge.
The badge is optional. It mainly helps well-known brands reassure customers that they are talking to the real business.