The lagging strand is one of the two strands of DNA that are synthesized during DNA replication. Unlike the leading strand, which is made continuously, the lagging strand is synthesized in short segments called Okazaki fragments. This occurs because DNA polymerase can only add nucleotides in a 5' to 3' direction, requiring the lagging strand to be built in the opposite direction of the replication fork. During replication, the lagging strand is formed as the DNA unwinds, creating a series of short segments that are later joined together by the enzyme DNA ligase. This process ensures that both strands of the DNA double helix are accurately copied, allowing for proper cell division and genetic inheritance.