The pre-wash cycle in a washing machine is designed for cleaning particularly dirty clothes that need a bit of extra washing. It rinses your clothes in cold water before the main wash, removing dirt so your clothing can be cleaned better by the main wash cycle. You can add detergent and optionally stain remover in a pre-wash cycle, or just let it rinse your clothes with water alone.
Is the pre-wash cycle necessary?
In the past, washing machines and laundry detergents were less sophisticated and it often took longer to get clothes properly clean. These days however, it is possible to clean heavily soiled clothes well on a regular cycle.
According to this article, the pre-wash cycle is unnecessary. Since the pre-wash cycle uses about 15 litres of water and doesn’t offer much of an improvement to just washing clothes in the regular cycle, it’s best to use it sparingly, if at all.