A spa is a location where mineral-rich spring water is used to give medicinal baths. Spa towns or spa resorts typically offer various health treatments, which are also known as balneotherapy. The belief in the curative powers of mineral waters goes back to prehistoric times. Such practices have been popular worldwide, but are especially widespread in Europe and Japan. Day spas and medspas are also quite popular, and offer various personal care treatments.

Mineral water is water from a mineral spring that contains various minerals, such as salts and sulfur compounds. It is usually still, but may be sparkling (carbonated/effervescent).