A gamete is a sex cell that is formed in the gonads (testes in males and ovaries in females). 

Sexual reproduction involves the formation of gametes which is also known as gametogenesis. 

Gametogenesis in males is known as spermatogenesis which involves the formation of sperm whereas, in females, it is known as oogenesis which involves the formation of the ovum (egg cell). Each gamete is haploid and carries only one set of chromosomes. 

Sexual reproduction is marked by the fusion of gametes to form a zygote at the end of fertilization.