The usual way of reading and writing of the dna strand is from 5’ to 3’. When the dna strand is duplicated one strand is duplicated in the usual way and the other in inverse (because the strands are inverse directioned in the dna). The strand that is duplicated in the usual 5’ > 3’ is continuous and therefore leading. But the inverse cannot be duplicated in a continous line so its lagging and duplicated in fragments which are afterwards being connected with enzymes
