Diablo II/Items

Gems
Gems are equipment enhancing items that only take up one slot of inventory space. You place them within socketed equipment and once placed, they can never be removed.

Potions
Potions are split into two main categories, recovery and ailment curing.

Recovery
Recovery potions help refill your health or mana, or both!

Rejuvination
Rejuvenation potions heal both health and mana instantly rather than over time. Powerful, but often misused.

Stamina
Not so much of a remedy for an ailment, but it does cure "fatigue" by maxing out your Stamina for thirty seconds or so before it begins to drop like normal.

Antidote
Used to remove the poison status, antidotes are not commonly dropped and not commonly used since most poisons are slow acting and go away after a few seconds. Another way to remedy poison is to go to the town's magic user/potion seller; they will heal you and remove the poison effect.