How do we Advance Simulated Time?

After each clock update, all events that were scheduled to occur during this interval are identified. Events are considered to occur at the end of the interval and the system state are updated accordingly.
Useful to model system in which events occur only at intervals of some fixed length.
Disadvantages:
- wasteful scanning - no events happen during ?t
- accuracy problem - big ?t lost accuracy (assumes events occur only at multiple of ?t)