Ovoviviparous animals produce eggs that are fertilized and hatched inside their bodies rather than expelled. Certain types of insects, reptiles and fish give birth to live young in this way.
Ovoviviparous animals reproduce by fertilizing the egg within the female's womb. The egg comes to term inside the female's body then hatches before she expels the offspring. Oviparous animals, by contrast, expel their eggs and nurture them outside the female's body until they hatch.
Some ovoviviparous animals nourish their eggs until they hatch, while others, including insects, provide no nourishment until their offspring are born. Guppies are one well-known example of ovoviviparity.