There are two main types of tumors:

* Benign tumors: These tumors are non-cancerous. They do not spread to other parts of the body and are usually not life-threatening.

* Malignant tumors: These tumors are cancerous. They can invade surrounding tissues and spread to other parts of the body (metastasis).

It's important to note that the term "tumor" is not always used to describe a cancerous mass. Sometimes, it can refer to a localized swelling that is not cancerous, such as a cyst or an abscess.