Cell is the basic unit of life , it performs important functions in the body . cells make new cells by division and replace old dead cells . But in case of cancer cells divide abnormally and start growing uncontrollably which may spread to side by tissue , blood or lymph . These cells when collectively form a mass then called as tumor.

Tumor is of two type
Benign tumor – it is type of abnormal cell growth which is confined to one place only , it will not spread to other body parts.
Malignant tumor – it is the type of abnormal cell growth which will spread to other part of body.