Insulators are categorized by installation methods, including suspension insulators and pillar insulators; by the type of insulating material used, they are divided into porcelain insulators, glass insulators, and composite insulators (also known as synthetic insulators); by voltage class, they are classified as low-voltage and high-voltage insulators; by environmental conditions, there are dirt-resistant insulators for polluted areas; by voltage type, there are DC insulators; and there are also insulators for special purposes, such as insulating crossarms, semiconductor glaze insulators, tension insulators for distribution, spool insulators, and wiring insulators, etc. Additionally, they are further divided into A-type insulators, which are non-penetrable, and B-type insulators, which are penetrable, based on the possibility of insulation breakdown.