A humidor is any kind of box or room with constant humidity

Humidity

Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

, and ideal temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, used to store cigar

Cigar

A cigar is a tightly-rolled bundle of dried and fermented tobacco that is ignited so that its smoke may be drawn into the mouth. Cigar tobacco is grown in significant quantities in Brazil, Cameroon, Cuba, the Dominican Republic, Honduras, Indonesia, Mexico, Nicaragua, Philippines, and the Eastern...

s, cigarette

Cigarette

A cigarette is a small roll of finely cut tobacco leaves wrapped in a cylinder of thin paper for smoking. The cigarette is ignited at one end and allowed to smoulder; its smoke is inhaled from the other end, which is held in or to the mouth and in some cases a cigarette holder may be used as well...

s, or pipe tobacco. For private use, small wooden or acrylic glass humidor boxes for a few dozen cigars are used, while cigar shops may have walk-in humidors, sometimes consisting of a whole floor. Humidors can be used to store other goods for which a certain level of humidity is desirable; the Colorado Rockies

Colorado Rockies

The Colorado Rockies are a Major League Baseball team based in Denver, Colorado. Established in 1991, they started play in 1993 and are in the West Division of the National League. The team is named after the Rocky Mountains...

 Major League Baseball

Major League Baseball

Major League Baseball is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League...

 team stores game balls in a large humidor at their home stadium, Coors Field

Coors Field

Coors Field, located in Denver, Colorado, is the home field of Major League Baseball's Colorado Rockies. It is named for the Coors Brewing Company of Golden, Colorado, which purchased the naming rights to the park prior to its completion in 1995...

, to counteract the effects of Denver's high altitude and generally low humidity.
Humidors of all sizes use hygrometer

Hygrometer

A hygrometer is an instrument used for measuring the moisture content in the environmental air, or humidity. Most measurement devices usually rely on measurements of some other quantity such as temperature, pressure, mass or a mechanical or electrical change in a substance as moisture is absorbed...

s to keep track of the humidity levels.
Room humidor

Most common in cigar bars or stores.