A mechanical keyboard is a term usually used to categorize keyboards with high quality key switches. The term is sometimes defined as a keyboard that uses a switching mechanism which makes use of some sort of metal spring, or a switch that actuates at some point before the end of the switch's travel. These definitions are somewhat meaningless, given the huge variation in quality across different switch designs that have these properties. Consequently, some people prefer to use terms such as "high quality keyboards", or to refer to the keyboards by their specific switch type.
Traditionally, the term 'mechanical keyboard' referred to the typewriter-based keyboards that were common on computer consoles in the 1950s and 1960s, where the process of determining which key had been pressed was almost entirely electromechanical. In the 1970s, these were replaced with 'electronic' keyboards, which were keyboards that used digital circuitry to determine which keys had been pressed. However, as rubber dome keyboards become ubiquitous in the 1990s, companies began to market their microswitch-based keyboards as having 'mechanical' switches.