1. A Pawn which cannot be blocked or captured by an enemy pawn on its way to the promotion square
2. Usually very dangerous! (Fischer-Berliner)
3. But can be blockaded (XX) or played around (Tartakower-Denker)

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[Event "Hastings 1945/46"]
[Site "Hastings ENG"]
[Date "1946.01.07"]
[EventDate "1945.12.28"]
[Round "9"]
[Result "1-0"]
[White "Savielly Tartakower"]
[Black "Arnold Denker"]
[ECO "B58"]
[WhiteElo "?"]
[BlackElo "?"]
[PlyCount "123"]

1. e4 c5 2. Ne2 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 d6 6. Be2 g6
7. Be3 Bg7 8. h3 O-O 9. Qd2 d5 10. exd5 Nxd5 11. Nxd5 Nxd4
12. Bxd4 Qxd5 13. Bxg7 Qxg2 14. O-O-O Kxg7 15. Qe3 Qc6 16. Bg4
Qf6 17. Rd4 Bf5 18. Bxf5 Qxf5 19. h4 Rac8 20. c3 h5 21. Rg1
Rc6 22. Rg5 Qe6 23. Ra5 Qxe3+ 24. fxe3 a6 25. Rd7 Re6 26. Rxb7
Rd8 27. Kc2 Rxe3 28. Rxa6 Re2+ 29. Kb3 Rdd2 30. Ka3 g5
31. hxg5 h4 32. Rh6 f6 33. Rxf6 h3 34. Rh6 h2 35. Rb4 Rg2
36. Rh3 Rxg5 37. Rbh4 Ra5+ 38. Kb4 Rxa2 39. b3 Kf7 40. c4 Rab2
41. Kc5 h1=Q 42. Rxh1 Rxb3 43. Re4 Rb7 44. Kc6 Rbb2 45. Rh7+
Kf6 46. Rhxe7 Rdc2 47. c5 Rb3 48. R4e6+ Kf5 49. Re2 Kf6
50. R7e6+ Kf7 51. Rxc2 Kxe6 52. Re2+ Kf7 53. Kc7 Rc3 54. c6
Rc1 55. Kd7 Rd1+ 56. Kc8 Rc1 57. c7 Rb1 58. Re4 Rb2 59. Kd7
Rd2+ 60. Kc6 Rc2+ 61. Kd6 Rc1 62. Re5 1-0