Here's a breakdown of why motion sensors are popular for indoor security:

* Reliable: They detect movement using passive infrared (PIR) technology, which senses changes in heat and movement.

* Versatile: Motion sensors can be used in various settings, including homes, businesses, and warehouses.

* Affordable: Motion sensors are relatively inexpensive compared to other security options.

* Easy to Install: Many motion sensors are designed for easy DIY installation.

Here are some other terms you might see for motion sensors:

* Passive Infrared (PIR) Sensors

* Motion Detectors

* Security Sensors

Beyond motion sensors, some other indoor alarm devices include:

* Door/Window Sensors: These sensors detect when doors or windows are opened.

* Glass Break Sensors: These sensors detect the sound of breaking glass.

* Smoke Detectors: These sensors detect smoke and alert occupants of a fire.

* Carbon Monoxide Detectors: These sensors detect carbon monoxide, a colorless, odorless gas that can be deadly.

The specific type of alarm device that is best for you will depend on your individual needs and budget.