This tag is specific to Azure DDoS protection. It is not for generic DoS or DDoS usage.
Azure DDoS protection is described at https://review.learn.microsoft.com/en-us/azure/virtual-network/ddos-protection-overview.
DDoS Protection provides always-on network flow monitoring of the protected endpoints, and when a DDoS attack is detected, automatically applies mitigation to ensure only legitimate traffic reaches the service. DDoS Protection provides customers with the peace of mind that their services are protected from the impacts of DDoS attacks.