1. White gets a "Free" move
2. Blacks position collapses
An intermezzo (or Zwischenzug), an 'in-between' move, breaks the sequence of a seemingly forced series of captures and recaptures.
In position 1, it may have appeared that white was forced to recapture the knight on g3 and restore the material balance. But such is the harmony of white's pieces, white was able to play Ne4-d6 threatening the bishop on c8 before having to recapture on g3.
In position 2 (Polgar - Rogers, 1993), black had just played 40... Rxd4. Only to be greeted with 41.Bg6!, ignoring the rook. Should black play 41... fxB then 42. Qxe6+ wins. Practically any other move by black, and 42. Bh7+ wins, owing to back rank threats and Bxf5. Black played 41. RxR, and, after 42. Bh7+, resigned.
See: 'Operation'.