A small, T-shaped device inserted into the uterus and left in place long-term as a method to prevent conception. The two categories of intrauterine device (IUD) are: hormonal, using locally released progesterone (e.g., Mirena); and copper (e.g., ParaGard). Both are made primarily of plastic; ParaGard contains a spiral of copper around the vertical aspect of the device. Strings connected to the base of the device remain in place as a means for removal and assessing placement long-term and may be felt or visualized upon examination. IUDs do not protect against sexually transmitted infections.