DNA replication occurs in semi discontinuous manner. It means some portion of each parental strand is synthesized in continuous manner while rest is synthesized in discontinuous manner i.e. in small stretches. These small fragments of DNA are known as Okazaki fragments which are named so because their discoverer's name was Okazaki who was a Japanese scientist The portion which is synthesized in continuous manner is known as leading strand which always move towards replication fork in 5' to 3' direction. The strand which gets synthesized in small stretches is known as lagging strand which is synthesized in 5'-3' direction just like leading strand but Okazaki fragments are synthesized only when the directions of replication fork movement and replication are opposite.
