This topic doesn't apply to most mobile use cases. If you're using the iOS SDK or Android SDK, see [Initialize a mobile SDK](🔗), which describes getting the datafile and instantiating a client.
Once you have a datafile, you can instantiate an Optimizely client. Any time you retrieve an updated datafile, just re-instantiate the same client.
For simple applications, all you need to provide to instantiate a client is a [datafile](🔗) specifying the project configuration for a given environment. For most advanced implementations, you'll want to [customize the client](🔗) for your specific requirements.
There are several other optional parameters for configuring the Optimizely client. See the [Customize an SDK](🔗) and the API reference sections.