Changes salt ratio in the flesh to encourage the flesh to absorb moisture and thus avoid dry turkey breast. Formerly done by "broth" injection-- now soaking is known to work equally well. Brine can be flavored. The flesh's urge to absorb moisture due to the salt uptake means any flavoring agents are also absorbed into the depths of the meat.

Steps doing it matter-- easy to make bacteria grow if not done properly. Worth looking up and doing it well. (no here time now)

~S~