What is a proof set and where can i get them?

Proof Coin: Proof coinage means special early samples of a coin issue, historically made for checking the dies and for archival purposes, but nowadays often struck in greater numbers specially for coin collectors (numismatists). Nearly all countries have issued proof coinage.

Where can I get proof coins? The US Mint

Notes: 1. Proof coins are in ultra- high relief. 2. Proofs before 1936 are rare!