In tennis betting, a "hold" refers to a player successfully winning their serve during a game. When a player holds their serve, it means they have won the game while serving, which is crucial for maintaining a competitive edge in matches. Bettors may look at hold percentages—statistics indicating how often a player wins their service games—in order to gauge the strength of a player's serve and overall performance. High hold percentages often suggest a player is strong on their serve, potentially influencing betting odds and strategies for matches.