This study deals with final positions where even though black has lost on time, the result is still unclear. In most cases when one loses on time, the opponent is considered to have won the game and is given a full point. However, there are some exceptions where the opponent has insufficient mating material and the game is concluded in a draw.
The Fide Laws of Chess says that if one loses on time, then the opponent is given a victory only if he/she is able to checkmate the opponent king considering even the opponent's worst possible legal moves in the position. If there is no legal possible way to checkmate the opponent king then it's said to be a draw.
I've covered almost all the close to real occurring cases in this study. However, there are numerous hypothetical cases that are typically a fortress and no possible entry point to territories which also leads to draws even if one loses on time.