Hydrocarbon resins are defined as thermoplastic polymers which made from petroleum based feedstocks either aliphatic or aromatic carbons monomers. It has a tackifying effect and is suitable for use in applications where tackiness is required, such as adhesives and paints. There are two basic categories of hydrocarbon tackifier resins, aliphatic hydrocarbon resins and aromatic hydrocarbon resins.

Aliphatic hydrocarbon are generally polymers with five carbons aliphatic monomers. These C5 resins have Gardner colors between 1.5 to 6 (from light yellow to light brown) and are mostly used to tackify aliphatic polymers. These resins are characterized by their low odor, bright color, excellent heat stability, and high weather resistance in comparison to aromatic hydrocarbon resins.  Aliphatic hydrocarbon resins are commonly used for hot melt road marking systems, adhesive tape, hot melt adhesives, asphalt additive, and tire additives.

Aromatic hydrocarbon resins are high molecular weight resins generally consists of nine carbon aromatic monomers.  They are also named as C9 resins.  They are based on aromatic feedstocks that undergo very little refining prior to the polymerization of the resin. They are usually dark in color within typical Gardner color between 6 to 10 (dark yellow to dark brown). They are used mainly in adhesives, printing inks, sealants, and paints. As a class, aromatic hydrocarbon resins have a distinctive aromatic odor. It is also used in various adhesives, rubber mixing and processing aids, paint and ink additives, and asphalt additives.