It is the duplication of a cell into two identical cells, which, naturally, replaces tissue.
When tissue is damaged, it has to be replaced quickly. Your cells receive the message that they have to multiply far more quickly than they normally do, so many of them begin , the process in which one cell becomes two identical cells. Since the two daughter cells are identical, they can begin functioning to their full capacity right away.
Here is a brief overview of mitosis:
Interphase – The cell gets bigger, duplicates DNA, makes more organelles, all in preparation to become 2 identical daughter cells.
Prophase – Nuclear membrane begins to dissolve. Spindle fibers appear at each end of the cell, ready to pull the chromosomes away.
Metaphase – Chromosomes align in the middle.
Anaphase – Chromosomes are pulled to opposite ends of the cell, with each end receiving identical DNA.
Telophase – The two new cells are beginning to be formed, each now identical to the initial parent cell.
Cytokinesis – The physical splitting of the cells, they are fully formed and functioning.