What is CAC?

From Wikipedia

Certified Acceptance Corporation (CAC) is a coin grade verification service. It was founded in 2007 to examine and evaluate coins that have been previously certified by Numismatic Guaranty Corporation (NGC) or Professional Coin Grading Service (PCGS). CAC examines a coin to determine whether, in its opinion, the coin is correctly, over-, or under-graded. Coins that are correctly graded will have a green tamper-evident holographic sticker affixed to their holders.

As a result, CAC-stickered coins fetch premiums in the coin market, including internet auctions conducted on eBay, and traditional floor auctions held by Heritage Auctions and Stack's Bowers Galleries. CAC has become an important force in the coin industry as its stickered coins are sought after by collectors looking for high quality.

Since its inception in late 2007, CAC has processed more than 350,000 coin submissions with a declared insurance value totaling more than $1.75 billion. It also has purchased more than $250 million worth of coins

CAC maintains a database of all coins that it has verified, containing specific data ranging from dates and mint marks to other feature designations.