I was looking at some code and saw an out of context comment about 'hysteresis.' I think I have figured out what the code does so my question doesn't involve anything specific. I simply do not understand what the term means or how it is applicable in programming. I looked around and saw some mathmatic definitions but would like some more information. From what I can tell Hysteresis has something to do with predicting or assuming a given state for X based on what has happened to X in the past?
Hysteresis characterizes a system whose behavior (output) does not only depend on its input at time t, but also on its past behavior, on the path it has followed.
A well-known device that exhibits hysteresis is a thermostat. Imagine a thermostat that would switch on and off heating at 70°F. When temperature is around 70°F, while fluctuating a bit, the thermostat would continually switch heating on and off. Generally, a thermostat is built with hysteresis: it will switch on heating at (say) 69°F, but switch off heating at 71°F. This avoids the continual switches.
EDIT: have a look at Wikipedia's article.