While you can have a hub-free smart home, it is worth mentioning the benefits of having a hub.

The built-in Wi-Fi and Bluetooth connectivity allow the smart hub to seamlessly sync up with the other smart devices in your home such as smart thermostats, lights, and entertainment systems. The Echo Plus speaker also has a Zigbee hub, if you don't want a screen.

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Benefits of Using a Hub. With a smart hub for your home, your system will know when you arrive home and automatically set a series of commands in motion, such as turning on your lights, starting your oven, raising or lowering the temperature on your thermostat and so much more.

With sensors, Alexa becomes a much more robust smart home system, letting you create Routines that turn on the lights when you enter a room, without having to use your voice.
This smart hub is also fitted with powerful stereo speakers, complete with a 3-inch woofer, that can be used to enjoy music, watch YouTube videos, or even listen to recipes while you prepare dinner. Instead, you configure everything to work through your hub and a single app on your phone. Kasa Smart Plug by TP-Link, Dual Outlet Smart Home WiFi Socket works with Alexa, Echo, Google Home & IFTTT, No Hub Required, Remote Control, 15 Amp, UL Certified (HS107) Kasa Smart $24.99 $ 24 . The most obvious benefit is you eliminate the need for a dozen different apps on your phone.