Explain the differences between simple diffusion, facilitated diffusion, and active transport across the cell membrane

Explain the differences between simple diffusion, facilitated diffusion, and active transport across the cell membrane. For each process, describe the direction of movement relative to the concentration gradient, whether cellular energy (ATP) is required, and the role of membrane proteins.

Discussion:
Why is active transport important for maintaining stable concentrations of ions and other substances inside a cell? Provide one biological example of active transport and explain how it helps the cell maintain homeostasis.