Chances are you have a Central Air Conditioning system installed or are planning on having a system installed in the future.
While an AC does remove some humidity (only as a byproduct of the cooling process), it is designed to control the temperature of your home. It is NOT a dehumidifier.
In the Spring and Fall when it is cool outside your AC is typically not running. It can however, feel damp inside the house. While running a dehumidifier in the basement will make it feel more comfortable, it is only drawing the moisture from that 1 room. A Central Dehumidifier removes the damp air from ALL the rooms in your home and replaces it with dry air.
This process not only makes you feel warmer, it improves the IAQ (indoor air quality). Too much humidity has the potential to cause mildew, mold and health related problems.
Central Humidifiers can run in conjunction with your AC or independently.
As with any HVAC product, there are many different models and sizes to choose from. To be sure you get what you need for your home and your needs, consult with a licensed, professional HVAC installer.