ATP-Binding Cassette Transporters, or ABC transporters, are a large family of proteins that help move various substances across cell membranes. They use energy from ATP (adenosine triphosphate) to transport molecules, including ions, drugs, and lipids, in and out of cells. This process is crucial for maintaining cellular function and homeostasis. These transporters are found in many organisms, from bacteria to humans, and play key roles in processes like nutrient uptake and waste removal. Some ABC transporters are involved in drug resistance, making it challenging to treat certain diseases, such as cancer and infections.