A Bird bath is a ceramic basin of water that birds can bathe in or drink from. A very shallow, gradually deepening birdbath that is safe from cats, kept clean, and refreshed frequently with clean water to avoid contamination and mosquitoes can attract many different species of birds. Two inches of water in the center is all that is needed for most backyard birds because they do not submerge their bodies, only dipping their wings to splash water on their backs. Bird baths need to be at an elevation that is safe from predators.
A birdbath requires regular maintenance. Maintenance may be as simple as a daily quick wash and refill, but it will depend on the birdbath materials. This is important because of the possible adverse health effects of birds drinking dirty water or water which may have become fouled with excrement. Fresh water is important. Concrete bird baths tend to become mossy and, therefore, slippery -- requiring an occasional scrubbing out with a stiff brush.