Dactylic meter is a rhythmic pattern built from dactyls, metrical feet made up of one stressed syllable followed by two unstressed syllables. In English verse, it can sound like DUM-da-da, and poets use it to shape a rolling, emphatic movement through a line.
Because English naturally favors other stress patterns, fully dactylic lines are less common than mixed or loosely dactylic ones.
Example
Mornings were golden and bright on the hill
Carried the voices of birds through the air