Intermediate polars (IPs) are a subclass of cataclysmic variables (CVs) that exhibit properties intermediate between those of non-magnetic CVs and magnetic CVs (polars). IPs are characterized by the presence of a magnetic field in the white dwarf primary star, but the field is not strong enough to synchronize the spin of the white dwarf with the orbital period of the system.

IPs are thought to be the missing link in the evolutionary sequence of CVs. Non-magnetic CVs are believed to evolve into IPs as the magnetic field of the white dwarf gradually increases. IPs then evolve into magnetic CVs once the magnetic field becomes strong enough to synchronize the spin of the white dwarf with the orbital period.

Several observations support the idea that IPs are the missing link in the evolution of CVs. First, IPs are found in a region of the CV parameter space that is intermediate between that of non-magnetic CVs and magnetic CVs. Second, the magnetic field strengths of IPs are typically stronger than those of non-magnetic CVs but weaker than those of magnetic CVs. Third, IPs exhibit a variety of physical properties that are intermediate between those of non-magnetic CVs and magnetic CVs.

The study of IPs is important for understanding the evolution of CVs. IPs provide insights into the processes by which magnetic fields are generated in white dwarfs and the role of magnetic fields in the evolution of CVs. Additionally, IPs are interesting astrophysical objects in their own right and offer a unique opportunity to study the physics of accretion in magnetic CVs.