An Okazaki fragment is a short segment of DNA that is synthesized during the replication of the lagging strand. DNA replication occurs in a semi-conservative manner, where each strand serves as a template for a new strand. The lagging strand is synthesized in small pieces because it runs in the opposite direction to the replication fork. These fragments are later joined together by the enzyme DNA ligase to form a continuous strand. Each Okazaki fragment typically ranges from 100 to 200 nucleotides in length in eukaryotes, while they can be shorter in prokaryotes.