A tea infuser is a small, perforated container with a removable screw-on lid to be filled with loose tealeaves and placed directly into a teapot before the hot water is added. Using a tea infuser prevents the loose leaves from floating into teacups when the tea is poured. However, if an infuser is used, it will take a little longer for the tea to be ready because the leaves will be confined in a small area, slowing the process of the hot water moving over the leaves to create tea.