A Magic match consists of a series of games that are played until one side has won a set number of games, usually two. Drawn games do not count toward this goal.
This rule is often incorrectly abbreviated ‘best of three’. While it is true that most matches are usually won as 2-0 or 2-1, draws can result in forth or even fifth games being played. Two Headed Giant matches, unlike regular two player matches, are played till one team has won a match.
If the round ends before a player has won the required number of games, the winner of the match is the player who has won the most games at that point.
If the round has ended and only one player has won a game then that player is the winner of that match because they have won the majority of games.
If both players have equal game wins, the match is a draw.
If the round has ended and the result is 1-1 or even 0-0 then the match is a draw.
The Tournament Organizer may change the required number of games to be won for any portion of the tournament as long as this choice is announced before the tournament begins.
For example, the Pro Tour finals are played until one player wins three games. While a local store can structure their tournment in this way, certain premier tournaments supported by Wizards, have a prescribed structure. Certain tournaments supported by Wizards may have a specified structure required to run it. If so, that structure supersedes this rule.
Match results, not individual game results, are reported to the DCI.
The results of these matches are sent to WoTC. They used to do something with these results in the form of planeswalker points. Now? Who knows. Post your conspiracy theory online.