The outsole is the bottom part of the shoe, in contact with the group. It can be made in many different types and ways. There are multiple different raw materials that can be used in a number of different ways. The most common methods for creating an outsole is:
Assembly - As an outsole can be constituted of more than one component or compound it needs to be put together. This is called assembly as the parts are assembled together. An assembled outsole is sometimes referred to as "man made". The components assembled can be created by injected processes, cut from boards of desired material and then worked into correct shape or a combination. It varies depending on purpose.
Injection - The process of injection/ direct injection is referring to extruding a molten material into a mold which gives the material a certain shape. As it cools down the material turns solid and can be removed from the mold. After it's been cleaned it´s ready to be used. Either it´s used in an assembly process to create an outsole but depending on purpose it can also be designed as a finished sole. In the latter it's normally referred to as a unit sole as the sole is one unit. An injected outsole can be in multiple colors if the mold supports this. Then the colors need to be injected at separate times not to mix in the mold. Materials that can be injected are: PVC, TPR, EVA among others.
Molded - A molded outsole is normally made by putting a heat sensitive material into a mold. Then heat the mold until the material melts, expands and fills the mold. The molds are left to cool and the outsole is removed and trimmed. Same as an injected sole it can be used in an assembly process or as a unit sole. Materials used in this process need to be thermo-reactive such as: Rubber or SBR.