Logia is one of the three Devil Fruit types. It is characterized by giving its user the ability to turn into a natural element or force of nature, making them intangible. (Even in the case of Ice, though not in the case of Darkness.) It is this feature that defines every Logia type seen so far, as a Devil Fruit power that changes the user's body to a tangible material would instead be considered a Paramecia type. Such is the case with the Gomu Gomu no Mi and Jozu's unnamed devil fruit, as they technically turn into their respective "elements", but aren't intangible.