This section is a review of the many switching devices invented for use in telephone exchanges. See the Appendix below for coverage on "The Essential Electrical Switch" and a tutorial video on electromechanical switching for exchanges. 
 
Primarily, the coverage here is focused on switch mechanics; how it works. A given switch is used multiple times in the fabric that creates the talking path end-to-end.  The switches are designed to route the "talking path", usually 2 or 3 wires per connection. One exception is is the "Sequence+" switch in the diagram below. Explore it to see its function. 

Don't confuse the switch name with it's sometimes namesake exchange. For example a crossbar switch is used in the Crossbar exchange. To appreciate how a given switch integrates into an exchange, see the master diagram on the Exchange Anatomy page.

The switch names in the diagram/menu are categorized based on what movements they use to make a connection; either linear motion, radial motion, both, or some other ways. So, most switches have either one or two degrees of freedom for moving its connecting arms to make a circuit.

This is not an exhaustive list. However, the ones here are either important because of their proven success or pure ingenuity. The hierarchy implies at least some inheritance nature. For example, the devices below "First Strowger" are influenced by this design. Also, the ordering, top to bottom, is by date, first to last (approximately).