Logia

Logia is one of the three Devil Fruit types, being the rarest out of all of them. This type of Devil Fruit allows the user to transform the composition of their body into a natural element at will, as well as create and control it.

The term Logia was first used when Professor Titan was explaining the devil fruit system to Surge

Overview
A Logia Devil Fruit is characterized by giving its user the ability to create, control, and transform their body into a natural element.

If all three of these requirements are not met, then the Devil Fruit cannot be classified as a Logia type. Devil Fruits that allow the user to create and control poison, wax, or any other substance, but do not allow the user's body to transform into that element are classified under Paramecia. Likewise, Devil Fruits that change the user's body into a substance but don't bestow the power to create and control said substance are also classified as Paramecia. Meanwhile, abilities such as the Mochi Mochi no Mi are not classified as Logia fruits since they do not involve natural elements, but because their properties are similar to that of a Logia, they are classified as "Special Paramecia".