History:
The word livery comes from the French livree meaning to liberate or bestow. It was used to describe giving to retainers, who provided domestic service to the nobles and aristocrats.
It came to mean the suit of clothes worn by menservants in the colors of the master who provides it and for whom they work. ( Think Downton Abbey) So from the stable boy through the page boys, each would wear his master's livery. The master wouldn't wear the livery, but he might have cufflinks or a ring using the same symbol. Many of the crest used on livery buttons descended from the crest which knights wore on top of their helmets. It enabled friend and foe to recognize each other in battle. Identifying livery buttons can be difficult because often the crest is shared by many families.