OTAA: join first, then communicate
Over-the-Air Activation, or OTAA, is the recommended activation method for most production deployments. The device sends a join request, the network validates it, and the device receives information used to create fresh session keys.
OTAA is beginner-friendly operationally because devices can be moved or rejoined with new session context instead of relying only on fixed preloaded session values.
In practical terms, OTAA keeps long-term identity and root-key material separate from the session keys used for normal traffic. That makes rejoin, recovery, and fleet operations cleaner.
ABP: manually personalized
Activation By Personalization, or ABP, skips the join procedure. The device is provisioned with values such as DevAddr and session keys ahead of time.
ABP can be useful for tests and constrained cases, but it is easier to make mistakes with frame counters, key rotation, and device movement. For most new LoRaWAN beginners, OTAA should be the normal path.
If ABP is used, document who owns each key, how frame counters are preserved across resets, and what happens when a device changes network or region.