What is the most common form of autophagy?

The most common form of autophagy in cells is macroautophagy, a highly conserved cellular process that involves the degradation and recycling of damaged or dysfunctional cellular components, such as organelles and proteins. 

During macroautophagy, the cell forms an autophagosome, a double membrane structure sequestering the target particle to be degraded. The autophagosome traverses the cell’s cytoplasm and fuses with a lysosome, forming an autolysosome, in which the contents of the autophagosome and the lysosome come in contact with each other. The lysosomal enzyme breaks down and digests the contents of the autophagosome. 

Macroautophagy plays a key role in maintaining cellular homeostasis by eliminating superfluous and toxic cellular components and recycling valuable biomolecules to be re-used as essential nutrients during times of stress or for building new cellular structures.