Pedipalps are the two appendages on the front of a spider's head. Other arachnids, and chelicerates that are not arachnids also have pedipalps. Some spiders seem to have ten legs and not eight, because these pedipalps look like an extra pair of legs. The pedipalps are used rather like arms. Spiders often use them to hold insects (for example crickets) for them to eat.
Male spiders also use pedipalps for mating. The male spiders make some silk, put sperm onto the silk, and then put their pedipalps into the sperm. The pedipalps then hold the sperm, and the spider can use it to mate with a female by putting them inside her epigynum.