user25603: I found many historic games unfinished.
Take this match as an example.
This is a match between Viswanathan Anand and Garry Kasparov in Ch World (match) (PCA) 1995. Anand lost this match as per the result. But I didn't find any confirmed checkmate in the last. Please somebody explain.

user15221: Checkmate is just one way a game can end. It can also end on time, game loss penalty, or resignation. If you can make your opponent convinced enough of the futility of their position that they resign, this counts just as much of a win as does a checkmate. That's not an "unfinished game", that's a game that finished with a resignation. It's up to every player to decide when they think their position is hopeless. If you don't see why Viswanathan Anand thought that he had no chance of winning ... well, that's probably part of why you're not World Champion.

user18809: High level players usually resign when they have a lost position. There's no point in continuing the game for thirty more moves when defeat is inevitable. Checkmate is actually a rare occurence in elite games. You'll find the same thing in more modern games, too.
While players have the right to keep playing, it is considered bad etiquette to not resign when a player has no realistic chance of scoring.

25603: <p>I found many historic games unfinished.<br />
<a href="https://www.chess.com/analysis/game/master/724719" rel="nofollow noreferrer">Take this match as an example.</a>
This is a match between Viswanathan Anand and Garry Kasparov in Ch World (match) (PCA) 1995. Anand lost this match as per the result. But I didn't find any confirmed checkmate in the last. Please somebody explain.</p>
 15221: <p>Checkmate is just one way a game can end. It can also end on time, game loss penalty, or resignation. If you can make your opponent convinced enough of the futility of their position that they resign, this counts just as much of a win as does a checkmate. That's not an &quot;unfinished game&quot;, that's a game that finished with a resignation. It's up to every player to decide when they think their position is hopeless. If you don't see why Viswanathan Anand thought that he had no chance of winning ... well, that's probably part of why you're not World Champion.</p>
 18809: <p>High level players usually resign when they have a lost position. There's no point in continuing the game for thirty more moves when defeat is inevitable. Checkmate is actually a rare occurence in elite games. You'll find the same thing in more modern games, too.</p>
<p>While players have the right to keep playing, it is considered bad etiquette to not resign when a player has no realistic chance of scoring.</p>
