Dress code: Informal attire
Informal attire, also called international business attire or Western business attire is a dress code, typified by a suit and necktie. On the scale of formality, informal attire is more formal than casual but less formal than semi-formal. It is more presentational than semi-casual, but offers more room for personal expression than semi-formal dress. Informal should not be confused with casual, not even smart casual — in loose common usage, many people refer to informal dress as semi-formal or formal and formal dress (in the technical sense — that is, white tie, black tie, and similar) as very formal; this usage is not accepted by authorities on dress codes.
If the above definition from Wikipedia does not offer you any guidance on what to wear, take a look at the picture below.