47 ( +1 | -1 ) Re:f3 is a quite logical move, it supports the centre pawn on e4 and supports a possible pawn rush with g4. Propably you are puzzled because in other openings f3 is a clear weaknes for the K-side, yet in the Dragon White usually castles Q-side so f3 is OK. The dragon is known for it's sharp play with a black pawn rush on the Q-side (towards the enemy King) and a white pawn rush on the K-side.. (yet white can choose for quiter lines by castling also K-side)
142 ( +1 | -1 ) its more to defend the g4 squarethe yugoslav Attack against the Sic Dragon as well as the English Attack in the open sicilian in general both use f3 in the opening. The reason for it is more to prevent Ng4 which would hit the Bishop that was brought from c1 to e3 and also defend the h6 square so that if you move the Queen(as white) to d2 creating a battery with the bishop on e3 before you have played f3 then black moving Ng4 is very strong as it will take the bishop off the board. and the dark bishop for white is usually needed to offset the power of the dragon bishop on g7 from attacking down the a1 -h8 diagonal especially when castled queenside. 1 e4 c5 2 Nf3 d6 3 d4 cxd 4 Nxd4 g6 5 Nc3 Bg7 6 Be3 Nf6 7 f3 -- here you need to defend the g4 square before creating the battery with Qd2(which also clears out for potential 0-0-0) if not 7 Qd2 Ng4 and white has to decide upon losing his initiative and kingside attack allowing the Bishop to be traded off for blacks knight. The longterm effects for white of not having the dark squared bishop will be that the Bishop on g7 will have an excellent diagonal and will be unopposed he will be blacks best minor piece an will defend well as well as attack so thats why you play f3. In fischer's games in the open sicilian i have seen him play h3 instead to defend g4 and later he played f4 and so on. but id be careful straying from mainline in the first 10 moves or so because those who play the sicilian dragon know the lines well and will punish you for mistakes.,.
34 ( +1 | -1 ) You can go to www.chess.fm and under the section towards the bottom of the page there is a section of video lectures by Dr. Danny Kopec IM, there is a link titled fischer illustration. The game that is analyzed shows how fischer used h3 to protect the g4 square and start a kingside attack accordingly... among other themes that are covered.