Holding is an enchantment that increases the storage capacity of certain items and blocks that store things. Its maximum level is IV.
Tomes of knowledge can be enchanted to hold more experience.
The following blocks and items can be enchanted to hold more items, fluids or energy:
Watering cans can be enchanted to hold more water.
All equipment added by Thermal Innovation can be enchanted to increase their capacity.
All equipment added by Redstone Arsenal can be enchanted to hold more energy.
Satchels can be enchanted to hold more items.