Free verse is the most common verse form in modern poetry; this extract of a poem (1861) by Walt Whitman, one of the pioneers of free verse, is an example of the way that verse can be both free in rhythm and at the same time strongly rhythmical:
Beat! beat! drums! blow! bugles! blow!
Through the windows--through doors--burst like a ruthless force,
Into the solemn church, and scatter the congregation,
Into the school where the scholar is studying;
Leave not the bridegroom quiet--no happiness must he have now with his bride,
Nor the peaceful farmer any peace, ploughing his field or gathering his grain,
So fierce you whirr and pound you drums--so shrill you bugles blow.