Oncogene: A gene that has the potential to cause cancer. In its normal state, an oncogene promotes cell growth; however, when mutated or expressed at high levels, it can help turn a normal cell into a tumor cell.
Metastasis: The process by which cancer spreads from the place where it first started to another part of the body. It's like seeds from those weeds being carried by wind to other parts of your garden where they start growing.
Tumor suppressor genes: These are like the gardeners of your cellular garden. They normally prevent uncontrolled cell growth (weeds) but if they fail or become inactive due to mutations, it can lead to excessive cell growth resulting in tumors.