Wax Pack
A "wax pack" is an unopened pack of baseball cards (or football, basketball, hockey, etc). The reason they are called wax packs is because from the 1930's until 1991, nearly all cards were packaged in wax paper wrapper that was sealed with wax on the back. Since wax stains on a card greatly diminish the condition and value, the wax pack method lost popularity as the sportscard hobby became more upscale. In 1988, Score introduced the first mainstream poly pack in 1988, but it wasn't until 1989 when Upper Deck brought foil packs to the hobby that marked the end of wax.
Even though wax packs are not being used by card companies anymore, the term "wax pack" is still used widely in the hobby today as a generic term for most unopened packs, even though actual wax-sealed packs are no longer being used by card makers.
When purchasing vintage wax-sealed packs, a buyer must be careful that the pack hasn't been opened, searched, and re-sealed. Look for signs of tampering suc as browning on the sealed area. The discoloration may come from an unskilled pack-searcher using a hot iron to re-melt the wax and inadvertantly burning it a bit. Another sign of fraud, is if you open your pack and find a wax-stained card in the middle of the pack. If there are any wax stains, it should only be on the card nearest the wax seal.