Theory:

Cytokinesis:
Mitosis completes duplicated chromosomes into daughter nuclei, But the cell itself is divided into daughter cells.
Cytokinesis is the process by which the cytoplasm of a parent cell divides into two daughter cells.
  • In the middle of the cell membrane, constriction appears.
  • It continues to deepen.
  • It further divides the cytoplasm into two, thus producing new daughter cells from the parent cell.
Cytokinesis_eukaryotic_mitosis.svg
Cytokinesis eukaryotic mitosis
Significance of mitosis:
The process of mitosis is a great significance in the life of an organism.
 
Maintenance of chromosome number: Mitosis involves an equational division resulting in diploid daughter cells' formation with the same chromosome number as that of a mother cell. It helps to maintain the diploid (\(2n\)) number of chromosomes in daughter cells.
 
Growth: All the somatic cells are formed by mitosis, and thus it plays a vital role in the growth, organ development and increase in body size of a multicellular organism.
 
Repair: This process helps to repair the damaged and wounded tissue by renewal the lost cells.
 
Regeneration: It is involved in the replacement of old and dead cells by forming new cells.
 
Reproduction: Unicellular organisms are multiplies by this method.
Info bit:
Age of our body cells:
• Cells of the eye lens, nerve cells of  cerebral cortex and most muscle cells last a lifetime but once dead are not replaced.
Epithelial cells lining the gut last only about \(5\)  days.
Average life of other gut cells is about \(15\) years.
 
Duration of cell replacement:

Skin cells  - about every two weeks.
Bone cells - about every ten years.
Liver cells - about every \(300\) – \(500\) days.
Red blood cells last for about \(120\) days and are replaced.
Reference:
https://upload.wikimedia.org/wikipedia/commons/e/e0/Cytokinesis_eukaryotic_mitosis.svg