Visions of the future have usually been vastly different from what was imagined by science fiction authors, and the 21st century has so far been devoid of flying cars and meals delivered in pill form. But the world has gone through major technological shifts in recent decades, with wireless and automated features becoming more common in homes.

Even if you haven't updated your home to dim the lights or open the blinds at your voice command, you can still benefit from a smart doorbell. This feature is often outfitted with technology such as a camera, motion sensor, or intercom to not only make it easier to see who's at the door, but also improve your home's security.

While traditional doorbells are hardwired into the home, smart doorbells are often wireless. The home improvement site HomeAdvisor says wired doorbells can typically only be heard in some areas of the home. They are also more likely to install and repair since the wiring needs to be drawn through the walls.

A wireless doorbell consists of a transmitter and a receiver. The transmitter runs on batteries and is located outside the home, while the receiver is connected to a traditional electrical outlet inside the home. When someone rings the bell, a signal is sent to the receiver, which emits a chime.

Countless homes have old wired doorbells which have become useless, since they burned out long ago and were never repaired. Wireless doorbells are much easier to repair; maintaining them is as simple as changing the batteries.

You can choose to set up multiple receivers so that the doorbell is audible in all parts of your home. Stefan Lucian Gheorghe, founder of the interior design and architecture site Homedit, says wireless doorbells can also be taken with you if you move.

While some wireless doorbells are simply limited to giving out a chime, others will incorporate a number of other features. The home security site Safewise says some smart doorbells will have a two-way audio system, essentially incorporating an intercom into the design. Some doorbells can be linked with home automation features such as door locks, allowing you to let people in. Others use facial recognition technology to let in recognized visitors.

Smart doorbells can incorporate security features as well. Many models have a camera, which sends a video to your smartphone or other mobile device when someone rings the bell. Some bells even have night vision so you'll be able to see people who visit after dark.

Doorbells that integrate a camera with a motion sensor will let you see anyone who comes to the door, even if they don't knock or ring the bell. The camera will start recording when it detects someone, and the footage is sometimes stored in the cloud. This feature can easily give a clear picture of a burglar or the thief who has been stealing your newspaper or delivery packages.

This added security can give a boost to your home values. Vector Security, a company based in Warrendale, Pa., says buyers are increasingly interested in home automation and smart security measures when choosing a home.

When installing a smart doorbell, make sure it is securely connected to the home. Wireless doorbells that are loosely attached can be stolen.