Teleo means to bring to an end or to achieve a goal.
Reactive means readily responsive to a perceptual stimulus.A Teleo-Reactive (TR) program is one whose actions are all directed toward achieving goals (the Teleo part) — in a way appropriate to the current, perceived state of the environment (the Reactive part). The TR approach offers a simple, elegant, and intuitive way of both programming and specifying robust, opportunistic, goal-directed robotic agent task behavior. TR programs are written in a manner that allows engineers to define the behaviour of the system for achieving specific goals while being responsive to changes in the state of the environment.
A TR program continuously monitors perceptual information as the state of the environment is changed — changed either by the effects of the program’s own actions, by exogenous events, or by information communicated to it. The program can react rapidly to this information to change or to modify goal-achieving actions or to abort sub-actions that are no longer appropriate.
The TR approach was introduced by Nils Nilsson at Stanford University in 1994 (see here). He and his students developed it further during the 1990s, and there has been much work on the approach since then (as will be described on this Web site).