There are three typical problems with plug sockets: the number of outlets cannot be increased or reduced; the shape is uniform; and large plugs interfere with each other. The best global solution is as follows: to standardize and modularize the production of national sockets, adding functional modules such as USB; have modules that rotate 180 °, solving the problem of plug interference between two adjacent sockets; and have sockets that can be moved with the appliance they are connected to.