Mizuhiki (水引 みずひき)
In Japan, strands of paper string (mizuhiki) are used to decorate gifts and ceremonial utensils in much the same way ribbons are used in the West. Not only are they colorful, but a mark of elegance and respect. When you attend a wedding ceremony, you put a congratulatory gift money in these envelopes. Also, when you attend a funeral, you put it in an envelope with a blackish design and hand it to the receptionist. It will be a very important courtesy in business, so please remember it well.
For attending a funeral, it is customary in Japan to bring a monetary gift in a special envelop called, "koden bukuro." It is readily available even at a convenience store. It looks like a black and white one in the photo, which is different from the colorful one for a wedding ceremony.