Reasoning and acting within the time constraints of the real world are among the most fundamental notions of intelligence. Understanding the nature and structure of such constraints can help to find a satisfying solution or find a relaxation when no solution can be found. Given certain explicit temporal relationships between events, we may have the ability to infer additional relationships which are implicit in those given. For example, the transitivity of "before" and "contains" may allow inferring information regarding the sequence of events. Such inferences are essential in story understanding, planning and causal reasoning. Temporal information may be qualitative where events are represented by abstract time points and time intervals, and we process and deduce relationships between them, such as pairs intersecting each other, one preceding, following or containing another, etc. Other information may be quantitative where durations can be measured, precise time stamps may be available, or numerical methods can be applied to understand a specific time line of events. We will explore a variety of these topics.