Your cells die. All the time.

Billions of cells die every day in your body. Some rush out, others groan.

They can die accidentally if injured or infected. Alternatively, if they outlive their natural lifespan or begin to fail, they may carefully stage a desirable demise, with their remains neatly stowed away.

Originally, scientists thought these were the only two ways an animal cell could die: by accident or by this neat and tidy version. But over the past two decades, researchers have accumulated many other cell death scenarios, some specific to certain cell types or situations. Understanding this array of death patterns could help scientists save the good cells and kill the bad ones, leading to treatments for infections, autoimmune diseases and cancer.

“There are a lot of different flavors here,” says Michael Overholtzer, a cell biologist at Memorial Sloan Kettering Cancer Center in New York. He estimates that there are now more than 20 different names to describe cell death varieties.

Here, Knowable Magazine presents a handful of classic and new ways in which cells kick things off.

Unexpected cell death: necrosis

Many bad things can happen to cells: they are injured or burned, poisoned or deprived of oxygen, infected by microbes, or otherwise diseased. When a cell dies accidentally, it is called necrosis.

There are several types of necrosis, but none are pretty: In gangrene, when cells lack blood, they rot. In other cases, dying cells liquefy, sometimes turning into a yellow material. Lung cells damaged by tuberculosis become pasty and white – the technical name for this type, “caseating necrosis,” literally means “cheese-like.”

Any form of death other than necrosis is considered “programmed”, that is, it is intentionally caused by the cell because it is damaged or has lost its usefulness.

A good and clean death: apoptosis

The two main categories of programmed cell death are “silent and violent,” says Thirumala-Devi Kanneganti, an immunologist at St. Jude Children’s Research Hospital in Memphis, Tennessee. Apoptosis, first named in 1972, is the original silent type: it is a clean, clear form of cell death that does not wake up the immune system.

This is useful when the cells are damaged or have served their function. Apoptosis allows tadpoles to shed tail cells when they become frogs, for example, or for human embryos to shed webbing between developing fingers.

The cell shrinks and becomes detached from its neighbors. The genetic material in the nucleus breaks into pieces that crumple, and the nucleus itself fragments. The membrane bubbles and blisters and the cell disintegrates. Other cells gobble up the pieces, keeping the tissue tidy.