A breastplate is a plate metal defence for the chest. It could be paired with a back plate from about 1370 onwards. This is sometimes termed back and breast.
Breastplates covering the upper chest with shoulder plates appear in literary sources in approximately 1340. However, no actual images exist before 1370 so how these early breastplates appeared is not known.
By the middle of the 14th century the breastplate had extended to mid torso with metal waist hoops (1360) that soon after developed into the fauld (1370's).
At around 1460 breastplates became separated into two parts to include a plackart which reinforced the bottom of the breastplate and allowed a greater degree of movement around the waist. By the end of the century a single piece breastplate reappeared.
The breastplate remained in use until the middle of the 17th century where it competed with the buff coat and was eventually abandoned by soldiers in the latter part of the 17th century.