The lordship, later principality of Piedmont (Italian: Piemonte, French: Piémont) was originally an appanage of the Savoyard county and as such its lords were members of the Savoy-Achaea branch of that illustrious house. The title was inherited by the elder branch of the dynasty in 1418, at about which time Savoy was elevated to ducal status and Piedmont to princely status. When the House of Savoy was given the Kingdom of Sardinia, the Savoyard's used the style of Prince of Piedmont for their heir apparent. This first came into use by Prince Victor Amadeus of Savoy.
The usage was retained when the House of Savoy became Kings of Italy, "Prince of Piedmont" becoming roughly equivalent to the British "Prince of Wales", the title bestowed to the Crown Prince.
When the House of Savoy became the ruling dynasty of Italy in 1861, they continued to use the title of Prince of Piedmont for the heir apparent but also began alternating it with a new title, the Prince of Naples.
Royal Standard of the Prince of Piedmont
Coat of arms of the
Prince of Piedmont