Absorption is a status effect that will impact a player's health bar in a positive manner by adding "extra hearts" in addition to a player's typical 20 ( x 10).
Like all status effects, it can be removed by drinking milk.
Absorption adds 4 () per level of extra health to the player. The hearts appear in a yellowish color as opposed to the typical red. Once enough damage has been taken by a player to deplete an absorption heart (or after the effect wears off), the extra hearts will disappear from the user's health bar permanently until a player gets the status effect back.
Sources of Absorption
Golden Apple- Grants a player Absorption effect for two minutes when eaten.
Notch Apple- Grants a player Absorption IV effect for two minutes when eaten.