Brown mice are the most common household mice. They can easily make a home in the cracks and crevices of a home, and they tend to become sedentary if they find an undisturbed location where they thrive and can easily access food and water sources.
Brown mice are very shy, and they will likely never come out when people are around. For the most part, they stay hidden when there is human activity around them, and they eventually come out at night to scavenge and search for food and water. Even when a mouse cannot be directly observed, it might be possible to find traces and signs of its presence. For instance, it's simple to spot and recognize mouse droppings or chew marks on food packages and other items.
Brown mice are not dangerous to humans, but their droppings can cause unsanitary conditions and spread disease. They can also contaminate food by reaching up to stovetops, tables, counters, and pantries.