A tea bag is a small, porous sealed bag containing tea leaves and used with water for brewing the beverage called tea, or herbs or spices for brewing herbal teas (also known as "tisane"). Tea bags are commonly made of filter paper, silk or food grade plastic. The bag contains the tea leaves while the tea is steeped, making it easier to dispose of the leaves, and performs the same function as a tea infuser. Some tea bags have an attached piece of string with a paper label at the top that assists in removing the bag while also displaying the brand and/or variety of tea.