In the sequential circuit, if the output changes during the high voltage period or low voltage period, it is called level triggering. In other words, the output changes during either high voltage or low voltage period- not during the edges like in edge triggering.
Thus, when an event triggers at the clock level, we call it level triggering. Assume lighting an LED according to level triggering. LED can turn on at any time during the high voltage. In other words, the event is triggered whenever a clock level is encountered. Considering examples; SR latch and D latch are some examples for latches with level triggering.
