Simply put, a rain garden is a depression, or swale, in the landscape that collects and stores rain water, allowing it to infiltrate the soil and not run off your property. Planted with the right plants that can thrive in both wet and dry conditions, a rain garden can add beauty and interest to your landscape year round.
Looking at the bigger picture, rain gardens reduce storm water runoff and allow for groundwater systems to recharge. This also reduces your need to irrigate your garden, saving water, money, and effort.