MLB.com is the official site of Major League Baseball. MLB.com is a source of baseball-related information, including baseball news, statistics, and sports columns. MLB.com is also a commercial site, providing online streaming video and streaming audio broadcasts of all Major League Baseball games to paying subscribers, as well as "gameday", a near-live streaming box score of baseball games for free. In addition, MLB.com sells official baseball merchandise, allows users to buy tickets to baseball games, runs fantasy baseball leagues (both free and paid), and runs auctions of baseball memorabilia.

MLB.com also contains the full, unabridged, official rules of the game, which can be useful for researching the rarely-invoked rules for unusual occurrences.