Organisms reproduce to pass on their genes and create new members of their species. If the organisms of a species all fail to reproduce then the species may become extinct.
Asexual reproduction does not involve sex cells or fertilisation. Only one parent is required, unlike sexual reproduction which needs two parents. Since there is only one parent, there is no fusion of gametes and no mixing of genetic information. As a result, the offspring are genetically identical to the parent and to each other. They are clones.
Bacteria reproduce asexually.
Asexual reproduction in plants can take a number of forms. Many plants develop underground food storage organs that later develop into the following year's plants. Potatos and daffodils are both examples of plants which do this.
A daffodil bulb at the beginning and end of the growing season, with a lateral bud where the new plant will grow.
Some plants such as the spider plant, Chlorophytum, produce side branches with plantlets on them. Other plants like strawberries, produce runners with plantlets on them.
Asexual reproduction in animals does occur in sea anemones and starfish, but it is much less common than sexual reproduction.