This is known as reduction division.
Human sex cells contain one chromosome from each of the 23 pairs.
The four gametes produced in meiosis are genetically different.
The process of independent assortment leads to all gametes being different.
Independent assortment and the random nature of fertilisation lead to variation in living organisms – no two organisms are the same (apart from identical twins).
During fertilisation the haploid nucleus of a sperm cell and the haploid nucleus of an egg cell fuse together to form a diploid zygote.