Draft Pick is type of Game Mode included in League of Legends.
History
The Draft Pick was included in the Season One Patch.[1] It took part in the competition system for the Season One Ranked Games.
Since September 20, 2011 Draft Mode has been made available for unranked games on the Summoner's Rift and the Crystal Scar.
Process
In 5v5 premade and 3v3 premade, the first phase of this draft process will provide the inviter of each team with the opportunity to ban the use of three champions. In unranked/normal draft, a random player will be selected as team captain. However, if there are some premade players, the one who invited the others will absorb their probabilities of being captain (for example, if it is 3 premades, the host would have 60% chances of being captain, his two partners would have 0%, and the two solo players would have 20% each). In ranked/draft, the player with the highest Elo will be selected as captain, and the order of the rest of the team is constructed from highest to lowest. Banned champions cannot be selected for use on either team, so choose wisely!
In organized play where teams are familiar with each other, champions that someone on the other team play exceptionally well are normally banned to try to gain an advantage. In solo queue, bans are normally reserved for champions that are widely considered to be overpowered and are likely to be picked.
Bans are done in an alternating format, each team banning a single champion until 6 champions have been banned. After bans have been dispensed by both sides, the teams will begin the draft process. During play, draft picks will be exclusive, meaning that a drafted champion will not be available for play by the opposing team. The team who received the first ban will begin the drafting process in a 1:2:2:2:2:1 draft format for the 5v5 brackets and a 1:2:2:1 format for the 3v3 bracket.
6 bans (3 per side) are allowed in Draft Mode. This means a player must have access to at least 16 champions in order to participate. Those 16 champions can be either owned by the player or belonging to the free rotation in case of normal draft, whereas in solo or duo ranked all 16 champions must be owned, since free champions are no longer allowed to be picked in ranked(but you can still pick free champions you own).
Selecting a champion that another player on your team owns will give you the ability to trade champions with the other player, provided he also owns the champion you selected. A clickable icon will appear to the right of your champion's portrait after all players have locked in their champions. When this icon is clicked, a confirmation box appears on your screen, and you can select accept or decline. This is useful for securing a powerful champion for your team early in the pick process, or if you are unsure you want to play the role you selected a champion for (e.g, a jungler might change his mind and want to be a top laner instead or vice versa.)
References
http://euw.leagueoflegends.com/news/normal-draft-mode-here-stay