Heraldry is an ancient science and historical discipline and it was born as an evolution of traditional symbolism, always used by men to express his own emotions, needs and to communicate.
The coat of arms bea around XI centruty to make more easy the recognition of the knights in the battle, but also to make out the families, their ranks, titles and the collateral branches.
During time heraldry rules have evolved, so in a coat of arms it's possible to discover if the armiger is noble or not, if he belongs to a chivalryc order, if he/she is a man or a woman, if he/she is single, married or widowed, if he/she is a laic or a clergy, if he had fiefs, or particular facts about a family, so to pass down across generations the history and the heritage of a family.
Unfortunately in our culture heraldry is considered more a noble heritage, ignoring the fact that it's purely a very useful graphic language.