A computer is made up of physical hardware and software that runs applications. This is a blanket term that covers everything from small electronics to full scale servers. Most people would say their personal computer or laptop is a computer because that’s the item they interact with daily but there are plenty of computers we unconsciously use including: ATMs, modern cars and smart TVs.
There is a grey area between objects with basic integrated circuits like a microwave and a fully fledged computer with a kernel and operating system. As more household objects like refrigerators or Nest thermostat become smarter and integrated with our digital devices these lines become even more blurred.