You can control Philips Hue lights multiple ways — that's one of the reasons they're so smart! How you control your lights depends on whether you have a Hue Bridge.
Without a Hue Bridge
Certain Philips Hue lamps and light fixtures come with a Dimmer switch, which can be used out of the box to turn on and off the lights, dim and brighten, and cycle through four preset light scenes (if purchased with a White ambiance bulb). If your lamp did not come with a Dimmer switch, you can only turn on and off the light.
With a Hue Bridge
If you pair your lights with a Hue Bridge, you can then operate all your lights within the Hue app. The Hue app offers far more functionality, allowing you to set up the Home & Away feature, create custom light scenes, and more. You can also use a smart home assistant to control your lights with your voice.

Your Hue light may have been physically switched off (e.g. by using a wall switch) or it is out of the operating range of the system. If you are still having issues, please contact Support.

You can see the status of your product and system updates in the Hue app:

Open the Hue app and tap on Settings at the bottom of the app screen.
Navigate to Software update to view all of your Bridges and products.
Up-to-date products have a green check mark next to their listing.
New updates will begin downloading automatically.

Enable automatic updates on your device to allow the Philips Hue app to update automatically. To see if your software is up to date, go to Settings > Software update in the Hue app.

You can set up two starter kits independently and switch between them in the Hue app, but you can't control both Hue Bridges at the same time. You can add the lightbulbs from both starter kits to one Bridge or assign them to separate Bridges.