This move is useful to avoid Bg4 in some lines.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... g8f6  4. d2d3  4... f8c5  5. b1c3 One of the hundreds of ways to play the Anti-Berlin system. This is only the fifth most popular move. 5... e8g8  6. e1g1  6... f8e8  7. c1e3  Curiously, this move, natural as it seems, is a serious mistake. 7... c6d4 Now Black is already clearly better. The problem is that the b5-bishop is in trouble. This knight jump gains strength because White cannot capture with the f3-knight due to the fork, a common pattern in many opening variations. This is one of the reasons why everyone should study games from different openings—it improves your pattern recognition, a crucial ability to achieve chess mastery. 8. b5a4  8... c7c6 Black prepares both b7-b5 and d7-d5.