The names male and female when referring to threads basically refer to the location of the threads themselves in relation to the part. When the ridges circling the part are located along the exterior surface, then it is said to be a male thread. Alternatively, when the thread ridges are found along the interior surface of the part, then it labeled as a female thread. To summarize, internal thread ridges are female while external thread ridges are male. The most common scenario when pairing together two parts is that a male thread will be used to connect with a female thread. When pairing of threads is done in this way, the ridges line up and the threads are rotated into each other, functioning as a securing mechanism.