Keeping neat appearance is the most basic social protocol. Every household has at least one mirror at home. Mirror itself is Yin material, and has the function of enlaring the energy of somethings coming in its' reflective range. On another side, it can expel away certain kind of energy depending on how it is placed. Fengshui in different rooms have different principles, mirror placement principles can be also different in different rooms. Therefore, mirror placement is not very simple.
In Fengshui subject, mirror placement includes mainly knowledge about mirror location, mirror size, the things collocating with mirror and mirror shape.
Feng Shui effects of mirrors
Fifteen basic taboos of mirror placement