Well, as FDMAXEY says, "since" refers to a point in time, where as "for" refers to a period of time. So: I have studied English since 2002 I have studied Enlgish since last year Both refer to a point in time. I have studied English for 2 years Refers to the time passed since the action began in the first place, not to the point in time when it started (as oppossed to "since"). Cheers

yes I agree. Be careful not to say what many German or French people say (for example): "I have been learning English since 2 years" this should be " for 2 years". But as FDmaxey said, you could say "I have been learning English since 2009"

You would use 'since' to refer to a point in time. "I've been employed here since 2004" You would use 'for' to refer to a period or range of time. "I've been employed here for seven years."