The leading strand is one of the two new strands of DNA that are synthesized during replication. It's called 'leading' because it is synthesized continuously in the direction towards the replication fork.
An enzyme that unwinds the double helix structure of a DNA molecule, creating two template strands for replication - one for leading and one for lagging strand synthesis.
Primase: An enzyme that creates RNA primers – starting points for leading-strand synthesis.