Booster drafting is the most common method of drafting used for 6- or 8-player drafts. Wizards of the Coast describes the format as follows:
[In a Booster Draft], each player at the table starts with three unopened booster packs. Instead of just opening your cards and building a deck, you and the other players at the table have to draft the cards for your decks.
At the start of a Booster Draft, each player opens a pack and picks the card he or she wants from it. (You can’t see the cards that the other players draft.) Then each player passes the rest of the pack to his or her left. You pick up the pack that was passed to you, select a card, and pass the rest to your left. This process continues until all the cards have been drafted.
Next, each player opens a second pack, but this time, you pass the pack to your right. After all those cards are drafted, you open the third pack and pass to the left again. At the end of the draft, each player has forty-five cards-and unlimited basic lands-to build a deck with.
In a cube drafting environment, instead of using a retail 15-card booster pack, we simply use packs of 15 cards randomly selected from a cube. Each player drafts 45 cards, and must use those cards to create a deck of at least 40 cards.
40-card decks most commonly consist of 17 lands and 23 spells (creatures, planeswalkers, instants, artifacts, etc.). Since each player drafts 45 cards, many of the cards drafted will not be included in your deck.
For more information, see Cube Drafting with Eight Players and Cube Drafting with Six Players.