Always use the authentication method appropriate for your API client's execution context. Server-side SDKs should use API key authentication (with `setKey()`) rather than session-based authentication, which is meant for client-side applications. **Why it matters:** - Server SDKs are designed to work with API keys for secure backend operations - Session-based authentication (`setSession()`) won't function properly in server contexts - Consistent authentication patterns improve maintainability across projects **Example - PHP Server SDK:** ```php $client = (new Client()) ->setEndpoint('https://.cloud.appwrite.io/v1') ->setProject('') ->setKey(''); // Correct: Using API key for server authentication // ->setSession(''); // Incorrect: Session auth doesn't work server-side ``` **Example - Kotlin Server SDK:** ```kotlin val client = Client() .setEndpoint("https://.cloud.appwrite.io/v1") .setProject("") .setKey("") // Correct: Using API key for server authentication // .setSession("") // Incorrect: Session auth doesn't work server-side ```