What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature ?

Explanation

An abnormal and uncontrolled division of cells is termed as Cancer.
The cancerous cells are different from the normal cells in the following ways.

In our body, the growth and differentiation of cells is highly controlled and regulated.
The normal cells show a property called contact inhibition.
The surrounding cells inhibits uncontrolled growth and division of cells.
The normal cells lose this property and become cancerous cells giving rise to masses of cells called tumors.
Transformation of normal cells into cancerous cells is induced by some physical, chemical and biological agents (carcinogens).