English opening is defined by 1.c4. It is semi closed or often called "flank" opening which can lead to many semi-closed positions such as Kings Indian, Queens Indian, Ben-Oni or some semi-open positions if black decides to counter it with 1. .. e5 which can often lead to reverse sicilian defenses. The most usefull characteristic of English is that it can transpose to a lot of different openings which are highly dependable on blacks first move. Black can proceed with ( 3 most commonly played ) ; 1. .. e5 ( leads often to sharp middlegame, often gets inverse sicilian.. ) 1. .. Nf6 ( Leads to Indian setups, can be good, but often time white can ignore such setups ) 1. .. c5 ( symmetrical variation, leads to closed and very positional setups. )