Here's a breakdown:

* Endocytosis is a process where a cell membrane engulfs a substance, forming a vesicle (a small, membrane-bound sac) that transports the substance into the cell's interior.

There are different types of endocytosis, but they all involve the cell membrane invaginating (folding inward) and then pinching off to enclose the desired substance.

Let me know if you'd like to know more about the different types of endocytosis!