# Key Concept: Feature

A Feature is an identifiable functionality of a software application. Features may be used to identify entire applications, software modules or a specific functionality such as Print, Save or Draw. Each Feature is assigned a unique identifier called a Feature ID.

When you protect a Mac executable or dynamic shared library with Sentinel LDK Envelope, you define a single Feature ID for the entire binary. If you wish to apply unique Features to separate components or functions, you must use Sentinel Licensing API.

NOTE If your application will be distributed with Sentinel HL Basic keys, you can use only the default Feature (Feature ID 0) to protect your binary.

### Related Topics

Defining Binary Protection Details