Due to the variety of electrical connector manufacturers, each has its own classification method. The connector structure is increasingly diversified, and the application field is also expanding, resulting in the internal connection of the 1-chip package of the aviation plug 2IC package pin and PCB connection. Typical connector IC socket. 3. Connection between printed circuit and conductor or printed board. A typical connector is a printed circuit connector. 4 connection of base plate and base plate. Typical connectors are cabinet type. 5 connection between equipment. The typical product is circular connector. There is some overlap between levels 3 and 4. Among the five levels of connectors, the products with the highest market volume are those of level 3 and level 5, while the products with the fastest growth are those of level 3. As for other types, many different types can be classified according to use, installation method, special structure, special performance, etc., which often appear in publications and manufacturers' promotional materials, but generally only to highlight a certain feature and use, the basic classification still does not exceed the above classification principles.