Should the bottom button of a vest be left undone?

Yes. The convention is to leave the bottom button open. It allows the vest to sit properly when you move and is the accepted standard in formal dressing.

Can I wear a vest without a jacket?

Yes. A vest over a formal shirt is a common smart casual combination and works well for Malaysian weather, particularly at outdoor weddings where a full jacket is uncomfortable.

Does the vest need to match the suit?

For a traditional three-piece, yes, the vest should match the suit fabric. A contrasting vest is a deliberate style choice and reads more relaxed and less formal.

How should a vest fit?

It should lie flat against the shirt with no pulling at the buttons, and cover the waistband so no shirt shows between vest and trousers when you stand.

What is the difference between a suit vest and a knit vest?

A suit vest is woven and structured, designed to match tailoring. A knit vest is softer and more casual, worn over a shirt or under a jacket for texture rather than formality.