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The English Opening (1.c4) is a popular choice at both club and master level, because it is a chess opening that suits all styles. Elite players as diverse as Magnus Carlsen, Fabiano Caruana and Vishy Anand include it in their repertoire. As White you can play aggressively or opt for a more strategic approach, depending on what kind of middlegame positions you are looking for.
For a club player who wants to reap the benefits of this multipurpose opening, understanding is much more important than deep theoretical knowledge. The Full English Opening teaches the fundamentals and is the first one-volume book that covers all major variations.