# Basic Concepts

Before using a DeH, you need to understand the following basic concepts.

Glossary | Description
--- | ---
BYOL | BYOL indicates the Bring Your Own License mode. If you have an OS or a software license (a license whose certified items include number of physical sockets and physical cores), you can migrate your services to the cloud platform using the Bring Your Own License (BYOL) mode. Then, you can continue to use your existing licenses.
Region | A region indicates the physical location of the data center where a DeH is located.
Availability zone (AZ) | A physical region where resources use independent power supply and networks. AZs are physically isolated but interconnected through an internal network. To enhance application availability, you are advised to create instances in different AZs.
Project | A project groups and isolates IaaS OpenStack resources, such as compute, storage, and network resources. A project can be a department or a team. Multiple projects can be created under one account.
DeH flavor | A DeH flavor specifies the DeH attributes, including the number of CPUs on the physical server (the number of sockets), number of physical cores, CPU model, memory size, and number of vCPUs.

Parent topic: Product Introduction