Legend has it that the custom of the bridal shower began several centuries ago when the daughter of a rich merchant fell in love with a poor young man. Her father disapproved and denied her a dowry, so before the couple was married, the townspeople "showered" them with gifts that enabled them to set up a home together. A shower is still an excellent way to provide a soon-to-be-married friend with practical gifts for her new home.
Hosts and Guests
According to tradition, a shower should not be thrown by the bride's immediate relatives, such as her mother, future mother-in-law, or sister, since it would appear that they were asking for gifts. The maid of honor or another good friend usually hosts, or several people, often bridesmaids, share the responsibility. It is common for a bride to have more than one shower; when this happens, the hosts should consult one another -- or the bride, if the showers aren't meant to be surprises -- about guest lists to avoid duplication. Showers are generally held from a couple of months to a couple of weeks before the wedding.
Because it is understood that guests should bring a present to a shower, it is not appropriate to invite people whom you don't plan to include in the wedding. One noted exception is an office shower; it is not usually possible to invite all of your colleagues to the wedding, but they may want to help you celebrate nonetheless. By the time the shower invitations are sent, the bride should have already registered for gifts; it is perfectly acceptable for hosts to include registry information in the invitations.